Added pdf implementation of conical gradient.
Also fixed an erroneous comment in the gpu implementation.
Review URL: https://codereview.appspot.com/6351076

git-svn-id: http://skia.googlecode.com/svn/trunk@4520 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/effects/GrGradientEffects.cpp b/src/gpu/effects/GrGradientEffects.cpp
index b1d1138..9d75965 100644
--- a/src/gpu/effects/GrGradientEffects.cpp
+++ b/src/gpu/effects/GrGradientEffects.cpp
@@ -451,7 +451,7 @@
     SkString r1Name("r1");
     SkString tName("t");
     SkString p0; // 4a
-    SkString p1; // 1/(2a)
+    SkString p1; // 1/a
     SkString p2; // distance between centers
     SkString p3; // start radius
     SkString p4; // start radius squared