Comment additions after r130109

Rubber stamped by Geoffrey Garen.

Updated comments to how array storage works.

* runtime/ArrayStorage.h:
* runtime/JSArray.cpp:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@130218 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/JavaScriptCore/ChangeLog

+2012-10-02  Michael Saboff  <msaboff@apple.com>
+
+        Comment additions after r130109 
+
+        Rubber stamped by Geoffrey Garen.
+
+        Updated comments to how array storage works.
+
+        * runtime/ArrayStorage.h:
+        * runtime/JSArray.cpp:
+
 2012-10-01  Mark Hahnenberg  <mhahnenberg@apple.com>
 
         Block freeing thread should sleep indefinitely when there's no work to do

Source/JavaScriptCore/runtime/ArrayStorage.h

@@ -41,6 +41,8 @@ namespace JSC {
 // setStorage() methods. It is important to note that there may be space before the ArrayStorage that 
 // is used to quick unshift / shift operation. The actual allocated pointer is available by using:
 //     getStorage() - m_indexBias * sizeof(JSValue)
+// All slots in ArrayStorage (slots from 0 to vectorLength) are expected to be initialized to a JSValue or,
+// for hole slots, JSValue().
 struct ArrayStorage {
     WTF_MAKE_NONCOPYABLE(ArrayStorage);
 private:

Source/JavaScriptCore/runtime/JSArray.cpp

@@ -245,7 +245,7 @@ void JSArray::getOwnNonIndexPropertyNames(JSObject* object, ExecState* exec, Pro
     JSObject::getOwnNonIndexPropertyNames(thisObject, exec, propertyNames, mode);
 }
 
-// This method makes room in the vector, but leaves the new space uncleared.
+// This method makes room in the vector, but leaves the new space for count slots uncleared.
 bool JSArray::unshiftCountSlowCase(JSGlobalData& globalData, bool addToFront, unsigned count)
 {
     ArrayStorage* storage = ensureArrayStorage(globalData);