Use size_t in GCIdleTimeHandler to fix undefined behaviour.

src/heap/gc-idle-time-handler.cc

Index: src/heap/gc-idle-time-handler.cc
diff --git a/src/heap/gc-idle-time-handler.cc b/src/heap/gc-idle-time-handler.cc
index 83e95acc0526f5c46740b1e8ddc4f32619577a14..5ff4017c233f071b742974b9fcf242609de03de3 100644
--- a/src/heap/gc-idle-time-handler.cc
+++ b/src/heap/gc-idle-time-handler.cc
@@ -1,9 +1,6 @@
 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-#include <climits>
-
-#include "src/v8.h"
 
 #include "src/heap/gc-idle-time-handler.h"
 
@@ -14,8 +11,8 @@ namespace internal {
 const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
 
 
-intptr_t GCIdleTimeHandler::EstimateMarkingStepSize(
-    int idle_time_in_ms, intptr_t marking_speed_in_bytes_per_ms) {
+size_t GCIdleTimeHandler::EstimateMarkingStepSize(
+    size_t idle_time_in_ms, size_t marking_speed_in_bytes_per_ms) {
   DCHECK(idle_time_in_ms > 0);
 
   if (marking_speed_in_bytes_per_ms == 0) {
@@ -23,15 +20,17 @@ intptr_t GCIdleTimeHandler::EstimateMarkingStepSize(
         GCIdleTimeHandler::kInitialConservativeMarkingSpeed;
   }
 
-  intptr_t marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
-  if (static_cast<intptr_t>(marking_step_size / idle_time_in_ms) !=
-      marking_speed_in_bytes_per_ms) {
+  size_t marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
+  if (marking_step_size / marking_speed_in_bytes_per_ms != idle_time_in_ms) {
     // In the case of an overflow we return maximum marking step size.
-    return INT_MAX;
+    return GCIdleTimeHandler::kMaximumMarkingStepSize;
   }
 
-  return static_cast<intptr_t>(marking_step_size *
-                               GCIdleTimeHandler::kConservativeTimeRatio);
+  if (marking_step_size > kMaximumMarkingStepSize)
+    return kMaximumMarkingStepSize;
+
+  return static_cast<size_t>(marking_step_size *
+                             GCIdleTimeHandler::kConservativeTimeRatio);
 }
 }
 }