Add dual source blending support for proper blending with coverage.

Review URL: http://codereview.appspot.com/4535088/



git-svn-id: http://skia.googlecode.com/svn/trunk@1390 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp b/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
index b494d76..0350c30 100644
--- a/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
+++ b/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
@@ -174,6 +174,7 @@
             // we must have FBOs
             return;
         }
+        GR_GL_GET_PROC(BindFragDataLocationIndexed);
         gDefaultInterface.fBindingsExported = kDesktop_GrGLBinding;
 
         gDefaultInterfaceInit = true;