[WSL] Cannot put templated structs inside structs

[WSL] Cannot put templated structs inside structs
https://bugs.webkit.org/show_bug.cgi?id=177120

Reviewed by Myles Maxfield.

It turns out that we still need to instantiate structs even if not passing type arguments,
since its fields may need to be instantiated.

This makes Myles's test case pass. When writing the test case, I encountered parser bugs, and
I fixed them.

* WebGPUShadingLanguageRI/CallFunction.js:
(callFunction):
* WebGPUShadingLanguageRI/Checker.js:
(Checker.prototype.visitReferenceType):
* WebGPUShadingLanguageRI/FuncInstantiator.js:
(FuncInstantiator.prototype.getUnique):
(FuncInstantiator):
* WebGPUShadingLanguageRI/Parse.js:
(parseSuffixOperator):
(parsePossibleSuffix):
(parsePostIncrement):
* WebGPUShadingLanguageRI/StructType.js:
(StructType.prototype.instantiate):
* WebGPUShadingLanguageRI/Test.js:
(checkNumber):
(checkEnum):
(TEST_instantiateStructInStruct):
* WebGPUShadingLanguageRI/TypeRef.js:
(TypeRef.prototype.get instantiatedType):
(TypeRef.prototype.get isPrimitive):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@222201 268f45cc-cd09-0410-ab3c-d52691b4dbfc