Make SkShader store localM directly rather than as a separate alloc.

May cause very slight GM changes in gpu two pt radial/conical radients.
Review URL: https://codereview.appspot.com/6821056

git-svn-id: http://skia.googlecode.com/svn/trunk@6221 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/gradients/SkTwoPointConicalGradient.cpp b/src/effects/gradients/SkTwoPointConicalGradient.cpp
index acd0eee..f93f660 100644
--- a/src/effects/gradients/SkTwoPointConicalGradient.cpp
+++ b/src/effects/gradients/SkTwoPointConicalGradient.cpp
@@ -677,25 +677,22 @@
 bool SkTwoPointConicalGradient::asNewEffect(GrContext* context,
                                             GrEffectStage* stage) const {
     SkASSERT(NULL != context && NULL != stage);
-
+    SkASSERT(fPtsToUnit.isIdentity());
+    // invert the localM, translate to center1, rotate so center2 is on x axis.
     SkMatrix matrix;
+    if (!this->getLocalMatrix().invert(&matrix)) {
+        return false;
+    }
+    matrix.postTranslate(-fCenter1.fX, -fCenter1.fY);
+
     SkPoint diff = fCenter2 - fCenter1;
     SkScalar diffLen = diff.length();
     if (0 != diffLen) {
         SkScalar invDiffLen = SkScalarInvert(diffLen);
-        matrix.setSinCos(-SkScalarMul(invDiffLen, diff.fY),
-                         SkScalarMul(invDiffLen, diff.fX));
-    } else {
-        matrix.reset();
-    }
-    matrix.preTranslate(-fCenter1.fX, -fCenter1.fY);
-
-    SkMatrix localM;
-    if (this->getLocalMatrix(&localM)) {
-        if (!localM.invert(&localM)) {
-            return false;
-        }
-        matrix.preConcat(localM);
+        SkMatrix rot;
+        rot.setSinCos(-SkScalarMul(invDiffLen, diff.fY),
+                       SkScalarMul(invDiffLen, diff.fX));
+        matrix.postConcat(rot);
     }
 
     stage->setEffect(SkNEW_ARGS(GrConical2Gradient, (context, *this, fTileMode)), matrix)->unref();