[platform] MacOS supports on-demand paging

https://developer.apple.com/library/mac/documentation/Performance/Conceptual/ManagingMemory/Articles/AboutMemory.html#//apple_ref/doc/uid/20001880-SW3

R=jochen@chromium.org

Review-Url: https://codereview.chromium.org/2278473002
Cr-Commit-Position: refs/heads/master@{#38877}

src/base/platform/platform-macos.cc

@@ -250,10 +250,7 @@ bool VirtualMemory::ReleaseRegion(void* address, size_t size) {
   return munmap(address, size) == 0;
 }
 
-
-bool VirtualMemory::HasLazyCommits() {
-  return false;
-}
+bool VirtualMemory::HasLazyCommits() { return true; }
 
 }  // namespace base
 }  // namespace v8