chakrashim: fix undefined values in inspector

When creating the wrapped objects we were copying the `undefined`
properties which were then being translated to `null` during
serialization.

Fixes nodejs#280

PR-URL: nodejs#284
Reviewed-By: Hitesh Kanwathirtha <hiteshk@microsoft.com>

deps/chakrashim/src/jsrtinspectorhelpers.cc

@@ -22,6 +22,7 @@
 
 #include "v8chakra.h"
 #include "jsrtinspectorhelpers.h"
+#include "jsrtutils.h"
 
 namespace jsrt {
   static const int JsrtDebugPropertyAttributeReadOnly = 4;
@@ -59,6 +60,13 @@ namespace jsrt {
     JsValueRef sourceVal = nullptr;
     IfJsErrorRet(JsGetProperty(sourceObj, propId, &sourceVal));
 
+    bool isUndefined;
+    IfJsErrorRet(jsrt::IsUndefined(sourceVal, &isUndefined));
+
+    if (isUndefined) {
+      return JsNoError;
+    }
+
     JsValueRef destVal = nullptr;
     if (convertFunc != nullptr) {
       IfJsErrorRet(convertFunc(sourceVal, &destVal));