Fix cut and paste error in memory tracking. MapSpace -> CellSpace.

Review URL: http://codereview.chromium.org/194100

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2878 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/spaces.h

@@ -1686,7 +1686,7 @@ class CellSpace : public FixedSpace {
 #endif
 
  public:
-  TRACK_MEMORY("MapSpace")
+  TRACK_MEMORY("CellSpace")
 };