[PE] Optimize FloatRect::EnclosingIntRect() and EnclosedRect()

Use ClampSub on integer values instead of clampTo<int> on float values.

This can improve record time by 3% on Android
(https://pinpoint-dot-chromeperf.appspot.com/job/14d64d9e440000
 click "Analyze benchmark results).

Change-Id: I8521a93caf821c551f342c551b5de84b6e35e092
Bug: 820467
Reviewed-on: https://chromium-review.googlesource.com/958292Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543264}

third_party/WebKit/Source/platform/geometry/FloatRect.cpp

@@ -220,14 +220,12 @@ FloatRect UnionRect(const Vector<FloatRect>& rects) {
 }
 
 IntRect EnclosedIntRect(const FloatRect& rect) {
-  // Compute the enclosed rect using float types directly rather than
-  // FlooredIntPoint(...) etc. to avoid triggering integer overflows.
-  FloatPoint location(ceilf(rect.X()), ceilf(rect.Y()));
-  FloatPoint max_point(floorf(rect.MaxX()), floorf(rect.MaxY()));
-  FloatSize size = max_point - location;
+  IntPoint location = CeiledIntPoint(rect.Location());
+  IntPoint max_point = FlooredIntPoint(rect.MaxXMaxYCorner());
+  IntSize size(ClampSub(max_point.X(), location.X()),
+               ClampSub(max_point.Y(), location.Y()));
   size.ClampNegativeToZero();
-  return IntRect(clampTo<int>(location.X()), clampTo<int>(location.Y()),
-                 clampTo<int>(size.Width()), clampTo<int>(size.Height()));
+  return IntRect(location, size);
 }
 
 IntRect RoundedIntRect(const FloatRect& rect) {

third_party/WebKit/Source/platform/geometry/FloatRect.h

@@ -35,6 +35,7 @@
 #include "platform/geometry/IntRect.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/Forward.h"
+#include "platform/wtf/SaturatedArithmetic.h"
 
 #if defined(OS_MACOSX)
 typedef struct CGRect CGRect;
@@ -239,13 +240,10 @@ inline bool operator!=(const FloatRect& a, const FloatRect& b) {
 
 // Returns a IntRect containing the given FloatRect.
 inline IntRect EnclosingIntRect(const FloatRect& rect) {
-  // Compute the enclosing rect using float types directly rather than
-  // FlooredIntPoint(...) etc. to avoid triggering integer overflows.
-  FloatPoint location(floorf(rect.X()), floorf(rect.Y()));
-  FloatPoint max_point(ceilf(rect.MaxX()), ceilf(rect.MaxY()));
-  FloatSize size = max_point - location;
-  return IntRect(clampTo<int>(location.X()), clampTo<int>(location.Y()),
-                 clampTo<int>(size.Width()), clampTo<int>(size.Height()));
+  IntPoint location = FlooredIntPoint(rect.Location());
+  IntPoint max_point = CeiledIntPoint(rect.MaxXMaxYCorner());
+  return IntRect(location, IntSize(ClampSub(max_point.X(), location.X()),
+                                   ClampSub(max_point.Y(), location.Y())));
 }
 
 // Returns a valid IntRect contained within the given FloatRect.