Fix uninitialized memory access

https://codereview.appspot.com/7657044/



git-svn-id: http://skia.googlecode.com/svn/trunk@8142 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLVertexArray.h b/src/gpu/gl/GrGLVertexArray.h
index b68e71d..5693f4a 100644
--- a/src/gpu/gl/GrGLVertexArray.h
+++ b/src/gpu/gl/GrGLVertexArray.h
@@ -62,7 +62,8 @@
     void notifyVertexBufferDelete(GrGLuint id) {
         int count = fAttribArrayStates.count();
         for (int i = 0; i < count; ++i) {
-            if (id == fAttribArrayStates[i].fVertexBufferID) {
+            if (fAttribArrayStates[i].fAttribPointerIsValid &&
+                id == fAttribArrayStates[i].fVertexBufferID) {
                 fAttribArrayStates[i].invalidate();
             }
         }