WebGL: add targets for WebGL 2 when check FBO targets

Source/core/html/canvas/WebGLRenderingContextBase.h

Index: Source/core/html/canvas/WebGLRenderingContextBase.h
diff --git a/Source/core/html/canvas/WebGLRenderingContextBase.h b/Source/core/html/canvas/WebGLRenderingContextBase.h
index 5217ebbb96bff676b23fde4166fab2ad8d98eca5..c106209381aa503efd8a2e013e5be8f67c6d96c0 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.h
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.h
@@ -881,6 +881,12 @@ protected:
     // used only to warn about use of obsolete functions.
     void printWarningToConsole(const String&);
 
+    // Helper function to validate the target for checkFramebufferStatus and validateFramebufferFuncParameters.
+    virtual bool validateFramebufferTarget(GLenum target);
+
+    // Get the framebuffer bound to given target
+    virtual RefPtrWillBeMember<WebGLFramebuffer> getFramebufferBinding(GLenum target);

[Ken Russell (switch to Gerrit), 2015/04/30 01:41:51]

I don't think it's necessary or correct to return RefPtrWillBeMember<T> here.
You should just return a WebGLFramebuffer* here and call
m_framebufferBinding.get(). See https://www.chromium.org/blink/blink-gc and the
linked design document.

[yunchao, 2015/04/30 02:42:49]

Done.

+
     // Helper function to validate input parameters for framebuffer functions.
     // Generate GL error if parameters are illegal.
     bool validateFramebufferFuncParameters(const char* functionName, GLenum target, GLenum attachment);