Make List.remove return boolean.

sdk/lib/web_sql/dartium/web_sql_dartium.dart

 /**
  * An API for storing data in the browser that can be queried with SQL.
  *
  * **Caution:** this specification is no longer actively maintained by the Web
  * Applications Working Group and may be removed at any time.
  * See [the W3C Web SQL Database specification](http://www.w3.org/TR/webdatabase/)
  * for more information.
  *
  * The [dart:indexed_db] APIs is a recommended alternatives.
  */
@@ skipping 351 matching lines @@
   }
 
   Map removeAt(int pos) {
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
   Map removeLast() {
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
-  void remove(Object object) {
+  bool remove(Object object) {
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
   void removeWhere(bool test(Map element)) {
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
   void retainWhere(bool test(Map element)) {
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
@@ skipping 68 matching lines @@
 
 @DocsEditable
 @DomName('SQLTransactionSync')
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 @Experimental
 abstract class _SQLTransactionSync extends NativeFieldWrapperClass1 {
   _SQLTransactionSync.internal();
 
 }