Small fix for parsing type parameter declarations

[gabelevi]

When you eat a token, it looks like Babylon automatically lexes the next token. Setting this.state.inType changes the behavior of the lexer, so it needs to be set before eating the type. This was causing trouble, since

type Foo<T = void> = T;

wouldn't parse, since we would eat the = token before setting this.state.inType = true, which meant void was lexed as an expression instead as a type.

However, the whole type parameter declaration should be parsed with this.state.inType = true anyway. Sometimes it was, like for functions and arrow functions, but often it was not. This change makes all type parameter declarations be parsed with this.state.inType = true.

[codecov-io]

Current coverage is 96.91% (diff: 100%)

Merging #83 into master will decrease coverage by <.01%

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