Added Blink-side support for EXT_blend_minmax WebGL extension

Source/core/html/canvas/WebGLExtensionName.h

 // Copyright 2014 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 WebGLExtensionName_h
 #define WebGLExtensionName_h
 
 namespace WebCore {
 
 // Extension names are needed to properly wrap instances in JavaScript objects.
 enum WebGLExtensionName {
     ANGLEInstancedArraysName,
+    EXTBlendMinMaxName,
     EXTFragDepthName,
     EXTShaderTextureLODName,
     EXTTextureFilterAnisotropicName,
     OESElementIndexUintName,
     OESStandardDerivativesName,
     OESTextureFloatLinearName,
     OESTextureFloatName,
     OESTextureHalfFloatLinearName,
     OESTextureHalfFloatName,
     OESVertexArrayObjectName,
     WebGLCompressedTextureATCName,
     WebGLCompressedTextureETC1Name,
     WebGLCompressedTexturePVRTCName,
     WebGLCompressedTextureS3TCName,
     WebGLDebugRendererInfoName,
     WebGLDebugShadersName,
     WebGLDepthTextureName,
     WebGLDrawBuffersName,
     WebGLLoseContextName,
     WebGLExtensionNameCount, // Must be the last entry
 };
 
 }
 
 #endif // WebGLExtensionName_h