Clean up AddIncludesForType in JSC bindings generators
https://bugs.webkit.org/show_bug.cgi?id=117297

Reviewed by Kentaro Hara.

Clean up AddIncludesForType in JSC bindings generators:
- Add JSC specific SkipIncludeHeader() subroutine and move
exceptions there.
- Remove special case for SerializedScriptValue by improving
the condition for callbacks: "JS" prefix is now only added to
headers in callbacks if they are wrapper types. Non-wrapper
types such as SerializedScriptValue do not have a JS*.h
header.

No new tests, code clean up.

* bindings/scripts/CodeGenerator.pm:
(SkipIncludeHeader):
- Reuse IsPrimitiveType() to avoid code duplication.
- Remove special case for String as this is not a valid IDL type
and it is not currently used.
* bindings/scripts/CodeGeneratorJS.pm:
(SkipIncludeHeader):
(AddIncludesForType):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@151283 268f45cc-cd09-0410-ab3c-d52691b4dbfc