Let AddDictionaryElement / AddFastElement purely add, move transition heuristics to AddDataElement

BUG=v8:4137
LOG=n

Review URL: https://codereview.chromium.org/1194023004

Cr-Commit-Position: refs/heads/master@{#29287}

src/objects.h

@@ -1899,9 +1899,6 @@ class JSObject: public JSReceiver {
   static void SetNormalizedProperty(Handle<JSObject> object, Handle<Name> name,
                                     Handle<Object> value,
                                     PropertyDetails details);
-  static void AddDictionaryElement(Handle<JSObject> object, uint32_t index,
-                                   Handle<Object> value,
-                                   PropertyAttributes attributes);
   static void SetDictionaryElement(Handle<JSObject> object, uint32_t index,
                                    Handle<Object> value,
                                    PropertyAttributes attributes);
@@ -2011,12 +2008,6 @@ class JSObject: public JSReceiver {
   // an access at key?
   bool WouldConvertToSlowElements(uint32_t index);
   inline bool WouldConvertToSlowElements(Handle<Object> key);
-  // Do we want to keep fast elements when adding an element at |index|?
-  // Returns |new_capacity| indicating to which capacity the object should be
-  // increased.
-  bool ShouldConvertToSlowElements(uint32_t capacity, uint32_t index,
-                                   uint32_t* new_capacity);
-  ElementsKind BestFittingFastElementsKind();
 
   // Computes the new capacity when expanding the elements of a JSObject.
   static uint32_t NewElementsCapacity(uint32_t old_capacity) {
@@ -2285,6 +2276,9 @@ class JSObject: public JSReceiver {
       Handle<JSObject> object, const char* type, Handle<Name> name,
       Handle<Object> old_value);
 
+  // Gets the current elements capacity and the number of used elements.
+  void GetElementsCapacityAndUsage(int* capacity, int* used);
+
  private:
   friend class DictionaryElementsAccessor;
   friend class JSReceiver;
@@ -2319,12 +2313,6 @@ class JSObject: public JSReceiver {
                                     ElementsKind kind,
                                     Object* object);
 
-  // Returns true if most of the elements backing storage is used.
-  bool HasDenseElements();
-
-  // Gets the current elements capacity and the number of used elements.
-  void GetElementsCapacityAndUsage(int* capacity, int* used);
-
   static bool CanSetCallback(Handle<JSObject> object, Handle<Name> name);
   static void SetElementCallback(Handle<JSObject> object,
                                  uint32_t index,

test/mjsunit/arguments.js

@@ -25,6 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Flags: --allow-natives-syntax
+
 function argc0() {
   return arguments.length;
 }
@@ -188,3 +190,17 @@ function arg_set(x) { return (arguments[x] = 117); }
 assertEquals(undefined, arg_get(0xFFFFFFFF));
 assertEquals(true, arg_del(0xFFFFFFFF));
 assertEquals(117, arg_set(0xFFFFFFFF));
+
+(function() {
+  function f(a) { return arguments; }
+  var a = f(1,2,3);
+  // Turn arguments into slow.
+  assertTrue(%HasSloppyArgumentsElements(a));
+  a[10000] = 1;
+  assertTrue(%HasSloppyArgumentsElements(a));
+  // Make it fast again by adding values.
+  for (var i = 0; i < 1000; i++) {
+    a[i] = 1.5;
+  }
+  assertTrue(%HasSloppyArgumentsElements(a));
+})();