Don't apply AA to rects with no rotation/perspective.

Change-Id: I21138d4d0589cc28f1dcffb8b675cd81a9900e24
diff --git a/libs/hwui/Matrix.cpp b/libs/hwui/Matrix.cpp
index e7c0fe3..9fc5131 100644
--- a/libs/hwui/Matrix.cpp
+++ b/libs/hwui/Matrix.cpp
@@ -67,6 +67,10 @@
             ALMOST_EQUAL(data[kScaleX], 1.0f) && ALMOST_EQUAL(data[kScaleY], 1.0f);
 }
 
+bool Matrix4::isSimple() {
+    return mSimpleMatrix;
+}
+
 void Matrix4::load(const float* v) {
     memcpy(data, v, sizeof(data));
     mSimpleMatrix = false;