super -> base

Runtime/widgets/automatic_keep_alive.cs

                                 this.GetType() +
                                 " created a Ticker via its TickerProviderStateMixin, but at the time " +
                                 "dispose() was called on the mixin, that Ticker was still active. All Tickers must " +
-                                "be disposed before calling super.dispose(). Tickers used by AnimationControllers " +
+                                "be disposed before calling base.dispose(). Tickers used by AnimationControllers " +
                                 "should be disposed by calling dispose() on the AnimationController itself. " +
                                 "Otherwise, the ticker will leak.\n" +
                                 "The offending ticker was: " + ticker.toString(debugIncludeStack: true)

Runtime/widgets/framework.cs

                 }
 
                 throw new UIWidgetsError(
-                    this._state.GetType() + ".dispose failed to call super.dispose.\n" +
+                    this._state.GetType() + ".dispose failed to call base.dispose.\n" +
                     "dispose() implementations must always call their superclass dispose() method, to ensure " +
                     "that all the resources used by the widget are fully released.");
             });

Runtime/widgets/ticker_provider.cs

                     this + " was disposed with an active Ticker.\n" +
                     this.GetType() + " created a Ticker via its SingleTickerProviderStateMixin, but at the time " +
                     "dispose() was called on the mixin, that Ticker was still active. The Ticker must " +
-                    "be disposed before calling super.dispose(). Tickers used by AnimationControllers " +
+                    "be disposed before calling base.dispose(). Tickers used by AnimationControllers " +
                     "should be disposed by calling dispose() on the AnimationController itself. " +
                     "Otherwise, the ticker will leak.\n" +
                     "The offending ticker was: " + this._ticker.toString(debugIncludeStack: true)
                                 this.GetType() +
                                 " created a Ticker via its TickerProviderStateMixin, but at the time " +
                                 "dispose() was called on the mixin, that Ticker was still active. All Tickers must " +
-                                "be disposed before calling super.dispose(). Tickers used by AnimationControllers " +
+                                "be disposed before calling base.dispose(). Tickers used by AnimationControllers " +
                                 "should be disposed by calling dispose() on the AnimationController itself. " +
                                 "Otherwise, the ticker will leak.\n" +
                                 "The offending ticker was: " + ticker.toString(debugIncludeStack: true)