add sk_float_isfinite to mask platform differences



git-svn-id: http://skia.googlecode.com/svn/trunk@2803 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/ScalarTest.cpp b/tests/ScalarTest.cpp
index 2848516..6c2df73 100644
--- a/tests/ScalarTest.cpp
+++ b/tests/ScalarTest.cpp
@@ -20,7 +20,7 @@
 }
 
 static bool isFinite_float(float x) {
-    return isfinite(x);
+    return sk_float_isfinite(x);
 }
 
 static bool isFinite_mulzero(float x) {