use 64bit math to compute is a rect is empty

Will work next to try to make isEmpty() private

Bug: skia:7470
Bug:799715
Change-Id: I7b43028ecd86dca68e0c67225712516d2f2f88a2
Reviewed-on: https://skia-review.googlesource.com/92620
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/core/SkAAClip.cpp b/src/core/SkAAClip.cpp
index c0707c5..b22b8eb 100644
--- a/src/core/SkAAClip.cpp
+++ b/src/core/SkAAClip.cpp
@@ -704,7 +704,7 @@
 }
 
 bool SkAAClip::setRect(const SkIRect& bounds) {
-    if (!SkRectPriv::PositiveDimensions(bounds)) {
+    if (bounds.isEmpty()) {
         return this->setEmpty();
     }