fix warning from scalar --> int32 conversion

BUG=

Review URL: https://codereview.appspot.com/7065050

git-svn-id: http://skia.googlecode.com/svn/trunk@7061 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/SkInterpolator.cpp b/src/utils/SkInterpolator.cpp
index 2ef2702..146adc2 100644
--- a/src/utils/SkInterpolator.cpp
+++ b/src/utils/SkInterpolator.cpp
@@ -81,7 +81,7 @@
         if (offsetTime >= endTime) {
             SkScalar fraction = SkScalarFraction(fRepeat);
             offsetTime = fraction == 0 && fRepeat > 0 ? totalTime :
-                SkScalarMulFloor(fraction, totalTime);
+                (SkMSec) SkScalarMulFloor(fraction, totalTime);
             result = kFreezeEnd_Result;
         } else {
             int mirror = fFlags & kMirror;