Implement support for dual source blending in ES

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 318426b5bc42097ebb95ac8f04f96ec1914fab23..70ef9a4f41abfc7fee11b24147a3c636c83ad294 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -271,8 +271,14 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
         fMultisampleDisableSupport = false;
     }
 
-    if (kGL_GrGLStandard == standard && version >= GR_GL_VER(3, 0)) {
-        fBindFragDataLocationSupport = true;
+    if (kGL_GrGLStandard == standard) {
+        if (version >= GR_GL_VER(3, 0)) {
+            fBindFragDataLocationSupport = true;
+        }
+    } else {
+        if (version >= GR_GL_VER(3, 0) && ctxInfo.hasExtension("GL_EXT_blend_func_extended")) {
+            fBindFragDataLocationSupport = true;
+        }
     }
 
     /**************************************************************************
@@ -295,6 +301,8 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
             ctxInfo.glslGeneration() >= k150_GrGLSLGeneration;
     }
     else {
+        glslCaps->fDualSourceBlendingSupport = ctxInfo.hasExtension("GL_EXT_blend_func_extended");
+
         glslCaps->fShaderDerivativeSupport = ctxInfo.version() >= GR_GL_VER(3, 0) ||
             ctxInfo.hasExtension("GL_OES_standard_derivatives");
     }