Bug 246559 – [WGSL] Flesh out WGSL AST

• Status: RESOLVED
• Resolution: FIXED
• Component: WebGPU

[Dan Glastonbury]

Only a partial AST is implemented.  After studying the WGSL specification, I propose:

```
Node
|- Attribute
|  |- AlignAttribute
|  |- BindingAttribute
|  |- BuiltinAttribute
|  |- ConstAttribute
|  |- GroupAttribute
|  |- IdAttribute
|  |- InterpolateAttribute
|  |- InvariantAttribute
|  |- LocationAttribute
|  |- SizeAttribute
|  |- StageAttribute
|  |- WorkgroupSizeAttribute
|- Directive
|- Expression
|  |- BinaryExpression
|  |- BitcastExpression
|  |- IndexAccessExpression
|  |- CallExpression
|  |- IdentiferExpression
|  |- LiteralExpression
|  |  |- BoolLiteral
|  |  |- FloatLiteral
|  |  |- IntegerLiteral
|  |- FieldAccessExpression
|  |- UnaryExpression
|- Function
|- ShaderModule
|- Statement
|  |- AssignmentStatement
|  |- BreakStatement
|  |- CallStatement
|  |- CompoundAssignmentStatement
|  |- CompoundStatement
|  |- ContinueStatement
|  |- DecrementStatement
|  |- DiscardStatement
|  |- ForStatement
|  |- IfStatement
|  |- IncrementStatement
|  |- LoopStatement
|  |- ReturnStatement
|  |- StaticAssertStatement
|  |- SwitchStatement
|  |- VariableStatement
|  |- WhileStatement
|- Structure
|- StructureMember
|- TypeAlias
|- TypeName
|  |- ArrayTypeName
|  |- NamedTypeName
|  |- ParameterizedTypeName
|- Value
|  |- ConstantValue
|  |- OverrideValue
|  |- LetValue
|  |- ParameterValue
|- Variable
|- VariableQualifier

```

[Radar WebKit Bug Importer]

<rdar://problem/101198259>

[Dan Glastonbury]

Pull request: https://github.com/WebKit/WebKit/pull/9369

[EWS]

Committed 259661@main (664eceb30ec0): <https://commits.webkit.org/259661@main>

Reviewed commits have been landed. Closing PR #9369 and removing active labels.