update getFramebufferAttachmentParameter for WebGL 2

Source/core/html/canvas/WebGL2RenderingContextBase.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebGL2RenderingContextBase_h
 #define WebGL2RenderingContextBase_h
 
 #include "core/html/canvas/WebGLExtension.h"
 #include "core/html/canvas/WebGLRenderingContextBase.h"
 #include "wtf/PassRefPtr.h"
@@ skipping 149 matching lines @@
     void bindVertexArray(WebGLVertexArrayObjectOES*);
 
     /* WebGLRenderingContextBase overrides */
     void initializeNewContext() override;
     void bindFramebuffer(GLenum target, WebGLFramebuffer*) override;
     ScriptValue getParameter(ScriptState*, GLenum pname) override;
     ScriptValue getTexParameter(ScriptState*, GLenum target, GLenum pname) override;
 
     DECLARE_VIRTUAL_TRACE();
 
+    ScriptValue getFramebufferAttachmentParameter(ScriptState*, GLenum target, GLenum attachment, GLenum pname) override;
+
 protected:
     WebGL2RenderingContextBase(HTMLCanvasElement*, PassOwnPtr<blink::WebGraphicsContext3D>, const WebGLContextAttributes& requestedAttributes);
 
+    // Helper function to validate target and the attachment combination for getFramebufferAttachmentParameters.
+    // Generate GL error and return false if parameters are illegal.
+    bool validateGetFramebufferAttachmentParameterFunc(const char* functionName, GLenum target, GLenum attachment);
+
     bool validateClearBuffer(const char* functionName, GLenum buffer, GLsizei length);
 
     ScriptValue getInt64Parameter(ScriptState*, GLenum);
 
     /* WebGLRenderingContextBase overrides */
     bool validateCapability(const char* functionName, GLenum) override;
     bool validateBufferTarget(const char* functionName, GLenum target) override;
     bool validateAndUpdateBufferBindTarget(const char* functionName, GLenum, WebGLBuffer*) override;
     WebGLTexture* validateTextureBinding(const char* functionName, GLenum target, bool useSixEnumsForCubeMap) override;
 
     RefPtrWillBeMember<WebGLFramebuffer> m_readFramebufferBinding;
 };
 
 DEFINE_TYPE_CASTS(WebGL2RenderingContextBase, CanvasRenderingContext, context,
     context->is3d() && WebGLRenderingContextBase::getWebGLVersion(context) >= 2,
     context.is3d() && WebGLRenderingContextBase::getWebGLVersion(&context) >= 2);
 
 } // namespace blink
 
 #endif