Add static assertions as requested in bug 726298 comment 2 and 4.

--HG--
extra : rebase_source : 3edf2446076dae08c16b121de18505174c84f370

js/public/HashTable.h

@@ -1062,7 +1062,7 @@ class HashMap
      */
     typedef typename Impl::Range Range;
     Range all() const                                 { return impl.all(); }
-    size_t count() const                              { return impl.count(); }
+    uint32_t count() const                            { return impl.count(); }
     size_t capacity() const                           { return impl.capacity(); }
     size_t sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const {
         return impl.sizeOfExcludingThis(mallocSizeOf);
@@ -1272,7 +1272,7 @@ class HashSet
      */
     typedef typename Impl::Range Range;
     Range all() const                                 { return impl.all(); }
-    size_t count() const                              { return impl.count(); }
+    uint32_t count() const                            { return impl.count(); }
     size_t capacity() const                           { return impl.capacity(); }
     size_t sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const {
         return impl.sizeOfExcludingThis(mallocSizeOf);

js/src/builtin/MapObject.cpp

@@ -288,7 +288,8 @@ JSBool
 MapObject::size(JSContext *cx, unsigned argc, Value *vp)
 {
     THIS_MAP(get, cx, argc, vp, args, map);
-    args.rval().setNumber(double(map.count()));
+    JS_STATIC_ASSERT(sizeof map.count() <= sizeof(uint32_t));
+    args.rval().setNumber(map.count());
     return true;
 }
 
@@ -457,7 +458,8 @@ JSBool
 SetObject::size(JSContext *cx, unsigned argc, Value *vp)
 {
     THIS_SET(has, cx, argc, vp, args, set);
-    args.rval().setNumber(double(set.count()));
+    JS_STATIC_ASSERT(sizeof set.count() <= sizeof(uint32_t));
+    args.rval().setNumber(set.count());
     return true;
 }