Move alpha-ramp AA to GrContext, detect cases when AA is applied via other methods (smooth lines, MSAA) or rect falls on integer coords and skip the alpha ramp path. Use pre-fab index buffer for alpha-ramped fill rects and stroke rects.

Review URL: http://codereview.appspot.com/4449047/

git-svn-id: http://skia.googlecode.com/svn/trunk@1169 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/GrGpuGL.cpp b/gpu/src/GrGpuGL.cpp
index 64431a3..f2ec450 100644
--- a/gpu/src/GrGpuGL.cpp
+++ b/gpu/src/GrGpuGL.cpp
@@ -361,6 +361,8 @@
         }
     }
 
+    fAALineSupport = GR_GL_SUPPORT_DESKTOP;
+
     ////////////////////////////////////////////////////////////////////////////
     // Experiments to determine limitations that can't be queried. TODO: Make
     // these a preprocess that generate some compile time constants.