Back out troublesome parts of patch for 130544 (147997, r/sr=me).

mailnews/base/util/nsMsgFolder.cpp

@@ -326,12 +326,12 @@ nsMsgFolder::SetElementAt(PRUint32 i, nsISupports* value) {
   return mSubFolders->SetElementAt(i, value);
 }
 
-NS_IMETHODIMP_(PRBool)
+NS_IMETHODIMP
 nsMsgFolder::AppendElement(nsISupports *aElement) {
   return mSubFolders->AppendElement(aElement);
 }
 
-NS_IMETHODIMP_(PRBool)
+NS_IMETHODIMP
 nsMsgFolder::RemoveElement(nsISupports *aElement) {
   return mSubFolders->RemoveElement(aElement);
 }

xpcom/ds/nsICollection.idl

@@ -48,8 +48,8 @@ interface nsICollection : nsISerializable
   void QueryElementAt(in PRUint32 index, in nsIIDRef uuid, 
                       [iid_is(uuid),retval] out nsQIResult result);
   void SetElementAt(in PRUint32 index, in nsISupports item);
-  [notxpcom] boolean AppendElement(in nsISupports item);
-  [notxpcom] boolean RemoveElement(in nsISupports item);
+  void AppendElement(in nsISupports item);
+  void RemoveElement(in nsISupports item);
 
   nsIEnumerator Enumerate();
 

xpcom/ds/nsSupportsArray.h

@@ -73,12 +73,12 @@ public:
   NS_IMETHOD SetElementAt(PRUint32 aIndex, nsISupports* value) {
     return ReplaceElementAt(value, aIndex) ? NS_OK : NS_ERROR_FAILURE;
   }
-  NS_IMETHOD_(PRBool) AppendElement(nsISupports *aElement) {
-    return InsertElementAt(aElement, mCount);
+  NS_IMETHOD AppendElement(nsISupports *aElement) {
+    return InsertElementAt(aElement, mCount)/* ? NS_OK : NS_ERROR_FAILURE*/;
   }
-  // NB: This may seem silly, but it implements nsICollection::RemoveElement.
-  NS_IMETHOD_(PRBool) RemoveElement(nsISupports *aElement) {
-    return RemoveElement(aElement, 0);
+  // XXX this is badly named - should be RemoveFirstElement
+  NS_IMETHOD RemoveElement(nsISupports *aElement) {
+    return RemoveElement(aElement, 0)/* ? NS_OK : NS_ERROR_FAILURE*/;
   }
   NS_IMETHOD_(PRBool) MoveElement(PRInt32 aFrom, PRInt32 aTo);
   NS_IMETHOD Enumerate(nsIEnumerator* *result);