Add ANGLE workaround to prefer flushes over VRAM usage

include/gpu/GrCaps.h

Index: include/gpu/GrCaps.h
diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index 48bcb28c4dfa21db368dbc6124126f1aaddea835..248135d691f20fa3d82884a1b8449ee5ff7e5d54 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -133,6 +133,8 @@ public:
         return fUseDrawInsteadOfPartialRenderTargetWrite;
     }
 
+    bool preferVRAMUseOverFlushes() const { return fPreferVRAMUseOverFlushes; }
+
     /**
      * Indicates the capabilities of the fixed function blend unit.
      */
@@ -249,6 +251,9 @@ protected:
     bool fUseDrawInsteadOfClear                      : 1;
     bool fUseDrawInsteadOfPartialRenderTargetWrite   : 1;
 
+    // ANGLE workaround
+    bool fPreferVRAMUseOverFlushes                   : 1;
+
     BlendEquationSupport fBlendEquationSupport;
     uint32_t fAdvBlendEqBlacklist;
     GR_STATIC_ASSERT(kLast_GrBlendEquation < 32);