Revert to enabling all of -O2 as it exposes a bug in the toolchain.

gm/bitmaprect.cpp

Index: gm/bitmaprect.cpp
diff --git a/gm/bitmaprect.cpp b/gm/bitmaprect.cpp
index 8b292837f321180ae7b5a011e1cd7dc9d86238f1..badffb9a939060c0e4bdd04c5a29bab3f559cae4 100644
--- a/gm/bitmaprect.cpp
+++ b/gm/bitmaprect.cpp
@@ -45,6 +45,13 @@ protected:
         return SkISize::Make(640, 480);
     }
 
+#ifdef SK_CPU_ARM64
+    // Skip tiled drawing on 64-bit ARM until https://skbug.com/2908 is fixed.
+    virtual uint32_t onGetFlags() const SK_OVERRIDE {
+        return kSkipTiled_Flag;
+    }
+#endif
+
     virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
         canvas->drawColor(0xFFCCCCCC);