Fix static assert on non-windows compilers(?)



git-svn-id: http://skia.googlecode.com/svn/trunk@4759 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index 21a553d..a46cedd 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -30,8 +30,7 @@
 const SkScalar gOneQuarter = SkFloatToScalar(0.25f);
 
 void setUniformPoint3(const GrGLUniformManager& uman, UniformHandle uni, const SkPoint3& point) {
-    GR_STATIC_ASSERT(offsetof(SkPoint3, fX) + sizeof(float) == offsetof(SkPoint3, fY));
-    GR_STATIC_ASSERT(offsetof(SkPoint3, fY) + sizeof(float) == offsetof(SkPoint3, fZ));
+    GR_STATIC_ASSERT(sizeof(SkPoint3) == 3 * sizeof(GrGLfloat));
     uman.set3fv(uni, 0, 1, &point.fX);
 }