IDL: Don't lose nullable flag when "preprocessing" type

Source/core/html/canvas/WebGLRenderingContextBase.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 181 matching lines @@
     void generateMipmap(GLenum target);
 
     PassRefPtrWillBeRawPtr<WebGLActiveInfo> getActiveAttrib(WebGLProgram*, GLuint index);
     PassRefPtrWillBeRawPtr<WebGLActiveInfo> getActiveUniform(WebGLProgram*, GLuint index);
     bool getAttachedShaders(WebGLProgram*, WillBeHeapVector<RefPtrWillBeMember<WebGLShader>>&);
     Nullable<WillBeHeapVector<RefPtrWillBeMember<WebGLShader>>> getAttachedShaders(WebGLProgram*);
     GLint getAttribLocation(WebGLProgram*, const String& name);
     ScriptValue getBufferParameter(ScriptState*, GLenum target, GLenum pname);
     void getContextAttributes(Nullable<WebGLContextAttributes>&);
     GLenum getError();
-    PassRefPtrWillBeRawPtr<WebGLExtension> getExtension(const String& name);

[Jens Widell, 2015/02/16 14:33:54]

This signature worked only by mistake. A method returning "object" is expected
to return ScriptValue, and the binding code will be

  v8SetReturnValue(info, <expression>.v8Value());

which compiles when <expression> is a ScriptValue, but not when it is what this
function returns.

However, this method was declared to return "object?", and there was a bug that
then disabled the conversion from "object" to "ScriptValue" (because the type
was nullable), the binding code ended up being

  v8SetReturnValue(info, <expression>);

which compiles fine when <expression> is what this function returns.

+    ScriptValue getExtension(ScriptState*, const String& name);
     ScriptValue getFramebufferAttachmentParameter(ScriptState*, GLenum target, GLenum attachment, GLenum pname);
     ScriptValue getParameter(ScriptState*, GLenum pname);
     ScriptValue getProgramParameter(ScriptState*, WebGLProgram*, GLenum pname);
     String getProgramInfoLog(WebGLProgram*);
     ScriptValue getRenderbufferParameter(ScriptState*, GLenum target, GLenum pname);
     ScriptValue getShaderParameter(ScriptState*, WebGLShader*, GLenum pname);
     String getShaderInfoLog(WebGLShader*);
     PassRefPtrWillBeRawPtr<WebGLShaderPrecisionFormat> getShaderPrecisionFormat(GLenum shaderType, GLenum precisionType);
     String getShaderSource(WebGLShader*);
     Nullable<Vector<String>> getSupportedExtensions();
@@ skipping 776 matching lines @@
     static IntSize oldestContextSize();
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif // WebGLRenderingContextBase_h