chore: Implement an implicit operator for creating normal completions

Whenever the spec tells us to return a value for a function that returns
a completion, it wants us to wrap that value in a normal completion.

Before we had to manually make a normal completion using the
NormalCompletion static functions.

However, it is much better to have an implicit operator that will call
NormalCompletion for us and makes the code a lot more readable.

JSS.Lib/AST/BitwiseNotExpression.cs

@@ -31,7 +31,7 @@ override public Completion Evaluate(VM vm)
         {
             // a. Return Number::bitwiseNOT(oldValue).
             var asNumber = oldValue.Value.AsNumber();
-            return Completion.NormalCompletion(Number.BitwiseNOT(asNumber));
+            return Number.BitwiseNOT(asNumber);
         }
         // 4. Else,
         else

JSS.Lib/AST/CallExpression.cs

@@ -105,7 +105,7 @@ private Completion ArgumentListEvaluation(VM vm)
             precedingArgs.Add(arg.Value);
         }
 
-        return Completion.NormalCompletion(precedingArgs);
+        return precedingArgs;
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/ComputedPropertyExpression.cs

@@ -46,7 +46,7 @@ private Completion EvaluatePropertyAccessWithExpressionKey(VM vm, Value baseValu
 
         // 4. Return the Reference Record { [[Base]]: baseValue, [[ReferencedName]]: propertyKey, [[Strict]]: strict, [[ThisValue]]: EMPTY }.
         var propertyString = propertyKey.Value.AsString();
-        return Completion.NormalCompletion(Reference.Resolvable(baseValue, propertyString.Value, Empty.The));
+        return Reference.Resolvable(baseValue, propertyString.Value, Empty.The);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/ConstDeclaration.cs

@@ -44,7 +44,7 @@ override public Completion Evaluate(VM vm)
         MUST(asReference.InitializeReferencedBinding(value.Value));
 
         // 6. Return EMPTY.
-        return Completion.NormalCompletion(Empty.The);
+        return Empty.The;
     }
 
     public string Identifier { get; }

JSS.Lib/AST/DebuggerStatement.cs

@@ -17,11 +17,11 @@ public override Completion Evaluate(VM vm)
             Debugger.Break();
 
             // b. Return a new implementation-defined Completion Record.
-            return Completion.NormalCompletion(Empty.The);
+            return Empty.The;
         }
 
         // 2. Else,
         // a. Return EMPTY.
-        return Completion.NormalCompletion(Empty.The);
+        return Empty.The;
     }
 }

JSS.Lib/AST/DoWhileStatement.cs

@@ -62,7 +62,7 @@ override public Completion Evaluate(VM vm)
             // f. If ToBoolean(exprValue) is false, return V.
             if (!exprValue.Value.ToBoolean().Value)
             {
-                return Completion.NormalCompletion(V);
+                return V;
             }
         }
     }

JSS.Lib/AST/EmptyStatement.cs

@@ -10,6 +10,6 @@ internal sealed class EmptyStatement : INode
     override public Completion Evaluate(VM vm)
     {
         // 1. Return EMPTY.
-        return Completion.NormalCompletion(Empty.The);
+        return Empty.The;
     }
 }

JSS.Lib/AST/ForStatement.cs

@@ -114,7 +114,7 @@ private Completion ForBodyEvaluation(VM vm)
                 // iii. If ToBoolean(testValue) is false, return V.
                 if (!testValue.Value.ToBoolean().Value)
                 {
-                    return Completion.NormalCompletion(V);
+                    return V;
                 }
             }
 

JSS.Lib/AST/FunctionDeclaration.cs

@@ -48,7 +48,7 @@ public FunctionObject InstantiateFunctionObject(Environment env)
     override public Completion Evaluate(VM vm)
     {
         // 1. Return EMPTY.
-        return Completion.NormalCompletion(Empty.The);
+        return Empty.The;
     }
 
     public string Identifier { get; }

JSS.Lib/AST/GreaterThanEqualsExpression.cs

@@ -37,10 +37,10 @@ override public Completion Evaluate(VM vm)
         if (r.IsAbruptCompletion()) return r;
 
         // 6. If r is either true or undefined, return false. Otherwise, return true.
-        if (r.Value.IsUndefined()) return Completion.NormalCompletion(new Boolean(false));
+        if (r.Value.IsUndefined()) return new Boolean(false);
 
         var rAsBoolean = r.Value.AsBoolean();
-        return Completion.NormalCompletion(new Boolean(!rAsBoolean.Value));
+        return new Boolean(!rAsBoolean.Value);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/GreaterThanExpreesion.cs

@@ -37,10 +37,10 @@ override public Completion Evaluate(VM vm)
         if (r.IsAbruptCompletion()) return r;
 
         // 6. If r is undefined, return false. Otherwise, return r.
-        if (r.Value.IsUndefined()) return Completion.NormalCompletion(new Boolean(false));
+        if (r.Value.IsUndefined()) return new Boolean(false);
 
         var rAsBoolean = r.Value.AsBoolean();
-        return Completion.NormalCompletion(new Boolean(rAsBoolean.Value));
+        return new Boolean(rAsBoolean.Value);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/IExpression.cs

@@ -51,7 +51,7 @@ static public Completion ApplyStringOrNumericBinaryOperator(Value lval, BinaryOp
                 var lstrValue = lstr.Value.AsString();
                 var rstrValue = rstr.Value.AsString();
                 var concatenation = lstrValue.Value + rstrValue.Value;
-                return Completion.NormalCompletion(new String(concatenation));
+                return new String(concatenation);
             }
 
             // d. Set lval to lprim.
@@ -99,7 +99,7 @@ static public Completion ApplyStringOrNumericBinaryOperator(Value lval, BinaryOp
         };
 
         var result = operation(lnum.Value.AsNumber(), rnum.Value.AsNumber());
-        return Completion.NormalCompletion(result);
+        return result;
     }
 
     // 13.15.4 EvaluateStringOrNumericBinaryExpression ( leftOperand, opText, rightOperand )

JSS.Lib/AST/IfStatement.cs

@@ -74,7 +74,7 @@ private Completion EvaluateWithoutElse(VM vm)
         if (!exprValue.Value)
         {
             // a. Return undefined.
-            return Completion.NormalCompletion(Undefined.The);
+            return Undefined.The;
         }
         // 4. Else,
         else

JSS.Lib/AST/LessThanEqualsExpression.cs

@@ -37,10 +37,10 @@ override public Completion Evaluate(VM vm)
         if (r.IsAbruptCompletion()) return r;
 
         // 6. If r is either true or undefined, return false. Otherwise, return true.
-        if (r.Value.IsUndefined()) return Completion.NormalCompletion(new Boolean(false));
+        if (r.Value.IsUndefined()) return new Boolean(false);
 
         var rAsBoolean = r.Value.AsBoolean();
-        return Completion.NormalCompletion(new Boolean(!rAsBoolean.Value));
+        return new Boolean(!rAsBoolean.Value);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/LessThanExpression.cs

@@ -37,10 +37,10 @@ override public Completion Evaluate(VM vm)
         if (r.IsAbruptCompletion()) return r;
 
         // 6. If r is undefined, return false. Otherwise, return r.
-        if (r.Value.IsUndefined()) return Completion.NormalCompletion(new Boolean(false));
+        if (r.Value.IsUndefined()) return new Boolean(false);
 
         var rAsBoolean = r.Value.AsBoolean();
-        return Completion.NormalCompletion(new Boolean(rAsBoolean.Value));
+        return new Boolean(rAsBoolean.Value);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/LetDeclaration.cs

@@ -43,7 +43,7 @@ private Completion EvaluateWithoutInitializer(VM vm)
         MUST(asReference.InitializeReferencedBinding(Undefined.The));
 
         // 3. Return EMPTY.
-        return Completion.NormalCompletion(Empty.The);
+        return Empty.The;
     }
 
     private Completion EvaluateWithInitializer(VM vm)
@@ -69,7 +69,7 @@ private Completion EvaluateWithInitializer(VM vm)
         MUST(asReference.InitializeReferencedBinding(value.Value));
 
         // 6. Return EMPTY.
-        return Completion.NormalCompletion(Empty.The);
+        return Empty.The;
     }
 
     public string Identifier { get; }

JSS.Lib/AST/Literal/BooleanLiteral.cs

@@ -17,7 +17,7 @@ override public Completion Evaluate(VM _)
     {
         // 1. If BooleanLiteral is the token false, return false.
         // 2. If BooleanLiteral is the token true, return true.
-        return Completion.NormalCompletion(_value);
+        return _value;
     }
 
     public bool Value

JSS.Lib/AST/Literal/NullLiteral.cs

@@ -10,6 +10,6 @@ internal sealed class NullLiteral : IExpression
     override public Completion Evaluate(VM vm)
     {
         // 1. Return null.
-        return Completion.NormalCompletion(Null.The);
+        return Null.The;
     }
 }

JSS.Lib/AST/Literal/NumericLiteral.cs

@@ -15,7 +15,7 @@ public NumericLiteral(double value)
     override public Completion Evaluate(VM _)
     {
         // 1. Return the NumericValue of NumericLiteral as defined in 12.9.3.
-        return Completion.NormalCompletion(_value);
+        return _value;
     }
 
     public double Value

JSS.Lib/AST/Literal/ObjectLiteral.cs

@@ -12,6 +12,6 @@ override public Completion Evaluate(VM vm)
     {
         // FIXME: Implement the rest of the evaluation when we parse property definitions
         // 1. Return OrdinaryObjectCreate(%Object.prototype%).
-        return Completion.NormalCompletion(new Object(ObjectPrototype.The));
+        return new Object(ObjectPrototype.The);
     }
 }

JSS.Lib/AST/Literal/StringLiteral.cs

@@ -15,7 +15,7 @@ public StringLiteral(string value)
     override public Completion Evaluate(VM _)
     {
         // 1. Return the SV of StringLiteral as defined in 12.9.4.2.
-        return Completion.NormalCompletion(_value);
+        return _value;
     }
 
     public string Value

JSS.Lib/AST/LogicalNotExpression.cs

@@ -26,7 +26,7 @@ override public Completion Evaluate(VM vm)
 
         // 3. If oldValue is true, return false.
         // 4. Return true.
-        return Completion.NormalCompletion(new Boolean(!oldValue.Value));
+        return new Boolean(!oldValue.Value);
     }
 
     public IExpression Expression { get; }

JSS.Lib/AST/LooseInequalityExpression.cs

@@ -38,7 +38,7 @@ override public Completion Evaluate(VM vm)
 
         // 6. If r is true, return false. Otherwise, return true.
         var rAsBoolean = r.Value.AsBoolean().Value;
-        return Completion.NormalCompletion(new Boolean(!rAsBoolean));
+        return new Boolean(!rAsBoolean);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/PrefixDecrementExpression.cs

@@ -49,7 +49,7 @@ override public Completion Evaluate(VM vm)
         if (putResult.IsAbruptCompletion()) return putResult;
 
         // 6. Return newValue.
-        return Completion.NormalCompletion(newValue);
+        return newValue;
     }
 
     public IExpression Expression { get; }

JSS.Lib/AST/PrefixIncrementExpression.cs

@@ -48,7 +48,7 @@ public override Completion Evaluate(VM vm)
         if (putResult.IsAbruptCompletion()) return putResult;
 
         // 6. Return newValue.
-        return Completion.NormalCompletion(newValue);
+        return newValue;
     }
 
     public IExpression Expression { get; }

JSS.Lib/AST/PropertyExpression.cs

@@ -26,7 +26,7 @@ override public Completion Evaluate(VM vm)
         // FIXME: 3. If the source text matched by this MemberExpression is strict mode code, let strict be true; else let strict be false.
 
         // 4. Return EvaluatePropertyAccessWithIdentifierKey(baseValue, IdentifierName, strict).
-        return Completion.NormalCompletion(EvaluatePropertyAccessWithIdentifierKey(baseValue.Value));
+        return EvaluatePropertyAccessWithIdentifierKey(baseValue.Value);
     }
 
     // 13.3.4 EvaluatePropertyAccessWithIdentifierKey, https://tc39.es/ecma262/#sec-evaluate-property-access-with-identifier-key

JSS.Lib/AST/StatementList.cs

@@ -15,7 +15,7 @@ public StatementList(List<INode> statements)
     override public Completion Evaluate(VM vm)
     {
         // 1. Let sl be ? Evaluation of StatementList.
-        Completion completion = Completion.NormalCompletion(Empty.The);
+        Completion completion = Empty.The;
         foreach (var statement in Statements)
         {
             // 2. Let s be Completion(Evaluation of StatementListItem).

JSS.Lib/AST/StrictEqualityExpression.cs

@@ -32,7 +32,7 @@ override public Completion Evaluate(VM vm)
         if (rval.IsAbruptCompletion()) return rval;
 
         // 5. Return IsStrictlyEqual(rval, lval).
-        return Completion.NormalCompletion(Value.IsStrictlyEqual(rval.Value, lval.Value));
+        return Value.IsStrictlyEqual(rval.Value, lval.Value);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/StrictInequalityExpression.cs

@@ -36,7 +36,7 @@ override public Completion Evaluate(VM vm)
         var r = Value.IsStrictlyEqual(rval.Value, lval.Value);
 
         // 6. If r is true, return false. Otherwise, return true.
-        return Completion.NormalCompletion(new Boolean(!r.Value));
+        return new Boolean(!r.Value);
     }
 
     public IExpression Lhs { get; }

JSS.Lib/AST/TypeOfExpression.cs

@@ -28,7 +28,7 @@ public override Completion Evaluate(VM vm)
             var asReference = val.Value.AsReference();
             if (asReference.IsUnresolvableReference())
             {
-                return Completion.NormalCompletion(new String("undefined"));
+                return new String("undefined");
             }
         }
 
@@ -39,43 +39,43 @@ public override Completion Evaluate(VM vm)
         // 4. If val is undefined, return "undefined".
         if (val.Value.IsUndefined())
         {
-            return Completion.NormalCompletion(new String("undefined"));
+            return new String("undefined");
         }
 
         // 5. If val is null, return "object".
         if (val.Value.IsNull())
         {
-            return Completion.NormalCompletion(new String("object"));
+            return new String("object");
         }
 
         // 6. If val is a String, return "string".
         if (val.Value.IsString())
         {
-            return Completion.NormalCompletion(new String("string"));
+            return new String("string");
         }
 
         // 7. If val is a Symbol, return "symbol".
         if (val.Value.IsSymbol())
         {
-            return Completion.NormalCompletion(new String("symbol"));
+            return new String("symbol");
         }
 
         // 8. If val is a Boolean, return "boolean".
         if (val.Value.IsBoolean())
         {
-            return Completion.NormalCompletion(new String("boolean"));
+            return new String("boolean");
         }
 
         // 9. If val is a Number, return "number".
         if (val.Value.IsNumber())
         {
-            return Completion.NormalCompletion(new String("number"));
+            return new String("number");
         }
 
         // 10. If val is a BigInt, return "bigint".
         if (val.Value.IsBigInt())
         {
-            return Completion.NormalCompletion(new String("bigint"));
+            return new String("bigint");
         }
 
         // 11. Assert: val is an Object.
@@ -86,11 +86,11 @@ public override Completion Evaluate(VM vm)
         // 13. If val has a [[Call]] internal slot, return "function".
         if (val.Value.HasInternalCall())
         {
-            return Completion.NormalCompletion(new String("function"));
+            return new String("function");
         }
 
         // 14. Return "object".
-        return Completion.NormalCompletion(new String("object"));
+        return new String("object");
     }
 
     public IExpression Expression { get; }

JSS.Lib/AST/UnaryMinusExpression.cs

@@ -31,7 +31,7 @@ override public Completion Evaluate(VM vm)
         {
             // a. Return Number::unaryMinus(oldValue).
             var asNumber = oldValue.Value.AsNumber();
-            return Completion.NormalCompletion(Number.UnaryMinus(asNumber));
+            return Number.UnaryMinus(asNumber);
         }
         // 4. Else,
         else