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 4611dc42c179fcf3d0d3cef4cc2019e7147d8911..5217ebbb96bff676b23fde4166fab2ad8d98eca5 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.h
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.h
@@ -212,7 +212,7 @@ 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);
@@ -796,7 +796,7 @@ 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.