update getTexParameter for WebGL 2

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 36bacf2cb78659797f3082f129126141bdc04c8d..f866356a5259c9beb6a974dbb1f14d1cf8aca781 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.h
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.h
@@ -209,7 +209,7 @@ public:
     PassRefPtrWillBeRawPtr<WebGLShaderPrecisionFormat> getShaderPrecisionFormat(GLenum shaderType, GLenum precisionType);
     String getShaderSource(WebGLShader*);
     Nullable<Vector<String>> getSupportedExtensions();
-    ScriptValue getTexParameter(ScriptState*, GLenum target, GLenum pname);
+    virtual ScriptValue getTexParameter(ScriptState*, GLenum target, GLenum pname);
     ScriptValue getUniform(ScriptState*, WebGLProgram*, const WebGLUniformLocation*);
     PassRefPtrWillBeRawPtr<WebGLUniformLocation> getUniformLocation(WebGLProgram*, const String&);
     ScriptValue getVertexAttrib(ScriptState*, GLuint index, GLenum pname);
@@ -782,7 +782,7 @@ protected:
     // Helper function to check target and texture bound to the target.
     // Generate GL errors and return 0 if target is invalid or texture bound is
     // null.  Otherwise, return the texture bound to the target.
-    WebGLTexture* validateTextureBinding(const char* functionName, GLenum target, bool useSixEnumsForCubeMap);
+    virtual WebGLTexture* validateTextureBinding(const char* functionName, GLenum target, bool useSixEnumsForCubeMap);
 
     // Helper function to check input format/type for functions {copy}Tex{Sub}Image.
     // Generates GL error and returns false if parameters are invalid.