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 54348196480b6cdabade965019006632809ed029..d5c3db7de7b747f5332b92b3e403050e893bab7f 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.h
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.h
@@ -883,6 +883,12 @@ 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 WebGLFramebuffer* getFramebufferBinding(GLenum target);
+
     // 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);