fix more 64bit warnings

BUG=skia:

Review URL: https://codereview.chromium.org/147683003

git-svn-id: http://skia.googlecode.com/svn/trunk@13190 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/SkLua.cpp b/src/utils/SkLua.cpp
index 8bc646f..9bbdc6c 100644
--- a/src/utils/SkLua.cpp
+++ b/src/utils/SkLua.cpp
@@ -1029,7 +1029,7 @@
 }
 
 static int lrrect_radii(lua_State* L) {
-    int corner = lua_tointeger(L, 2);
+    int corner = SkToInt(lua_tointeger(L, 2));
     SkVector v;
     if (corner < 0 || corner > 3) {
         SkDebugf("bad corner index %d", corner);