Change return type of MapSpace::NeedsCompaction from int to bool.

Fixes compiler warnings on Windows.

TBR=antonm@chromium.org

Review URL: http://codereview.chromium.org/549049

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3604 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/spaces.h

@@ -1778,7 +1778,7 @@ class MapSpace : public FixedSpace {
 
   // Should be called after forced sweep to find out if map space needs
   // compaction.
-  int NeedsCompaction(int live_maps) {
+  bool NeedsCompaction(int live_maps) {
     return !MapPointersEncodable() && live_maps <= kCompactionThreshold;
   }