Use static_assert instead of SK_COMPILE_ASSERT.

Now that static_assert is allowed, there is no need to use a non-
standard compile time assertion

Review URL: https://codereview.chromium.org/1306443004
diff --git a/gm/pixelsnap.cpp b/gm/pixelsnap.cpp
index 3358e9d..ea85a94 100644
--- a/gm/pixelsnap.cpp
+++ b/gm/pixelsnap.cpp
@@ -23,7 +23,7 @@
     static const int kSubPixelSteps = 8;
     static const int kLabelTextSize = 9;
 
-    SK_COMPILE_ASSERT(kSubPixelSteps < 99, label_offset_too_small);
+    static_assert(kSubPixelSteps < 99, "label_offset_too_small");
     static const int kLabelOffsetX = 2 * kLabelTextSize + kLabelPad;
     static const int kLabelOffsetY = kLabelTextSize + kLabelPad;