separate state for msaa renderability

R=robertphillips@google.com, brian@thesalomons.net

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/26695005

git-svn-id: http://skia.googlecode.com/svn/trunk@11770 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index 42b82f6..cd217f4 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -113,6 +113,10 @@
     if (kUnknown_GrPixelConfig == desc.fConfig) {
         return NULL;
     }
+    if ((desc.fFlags & kRenderTarget_GrTextureFlagBit) &&
+        !this->caps()->isConfigRenderable(desc.fConfig, desc.fSampleCnt > 0)) {
+        return NULL;
+    }
 
     this->handleDirtyContext();
     GrTexture* tex = this->onCreateTexture(desc, srcData, rowBytes);