Make the check for calling super.created not sensitive to line delimiters

tools/dom/templates/html/impl/impl_HTMLDocument.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING: Do not edit - generated code.
 
 part of $LIBRARYNAME;
 
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 $!MEMBERS
@@ skipping 264 matching lines @@
         createdParametersValid = true;                // Assume no parameters.
         if (methodMirror.parameters.length != 0) {
           // If any parameters each one must be optional.
           methodMirror.parameters.forEach((parameter) {
             createdParametersValid = createdParametersValid && parameter.isOptional;
           });
         }
 
         // Get the created constructor source and look at the initializer;
         // Must call super.created() if not its as an error.
-        var createdSource = methodMirror.source?.replaceAll('\n', ' ');
-        RegExp regExp = new RegExp(r":(.*?)(;|}|\n)");
-        var match = regExp.firstMatch(createdSource);
-        superCreatedCalled = match.input.substring(match.start,match.end).contains("super.created(");
+        var createdSource = methodMirror.source;
+        superCreatedCalled = createdSource.contains("super.created(");
       }
 
       if (!superCreatedCalled) {
         throw new DomException.jsInterop('created constructor initializer must call super.created()');
       } else if (!createdParametersValid) {
         throw new DomException.jsInterop('created constructor must have no parameters');
       }
 
       classMirror = classMirror.superclass;
       while (classMirror != classMirror.mixin) {
@@ skipping 94 matching lines @@
       //
       //                  MyElement.created() : super.created() {
       //                    this.innerHtml = "<b>I'm an x-foo-with-markup!</b>";
       //                  }
       //
       //              sanitizing causes custom element to created recursively
       //              until stack overflow.
       //
       //              See https://github.com/dart-lang/sdk/issues/23666
       int creating = 0;
-      // TODO(jacobr): warning: 
+      // TODO(jacobr): warning:
       elemProto['createdCallback'] = js.JsNative.withThis(($this) {
         if (_getJSClassName(reflectClass(customElementClass).superclass) != null && creating < 2) {
           creating++;
 
           var dartClass;
           try {
             dartClass = _blink.Blink_Utils.constructElement(customElementClass, $this);
           } catch (e) {
             dartClass = HtmlElement.internalCreateHtmlElement();
             dartClass._badUpgrade();
             throw e;
           } finally {
             // Need to remember the Dart class that was created for this custom so
             // return it and setup the blink_jsObject to the $this that we'll be working
-            // with as we talk to blink. 
+            // with as we talk to blink.
             js.setDartHtmlWrapperFor($this, dartClass);
 
             creating--;
           }
         }
       });
       elemProto['attributeChangedCallback'] = new js.JsFunction.withThis(($this, attrName, oldVal, newVal) {
         $this.attributeChanged(attrName, oldVal, newVal);
       });
       elemProto['attachedCallback'] = new js.JsFunction.withThis(($this) {
@@ skipping 66 matching lines @@
   /// parameter must be provided.
   @Experimental()
   ElementUpgrader createElementUpgrader(Type type, {String extendsTag}) {
 $if DART2JS
     return new _JSElementUpgrader(this, type, extendsTag);
 $else
     return new _VMElementUpgrader(this, type, extendsTag);
 $endif
   }
 }