Companion CL to support $0, $1, $2

tools/dom/src/native_DOMImplementation.dart

 // 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.
 
 part of html;
 
 class _ConsoleVariables {
   Map<String, Object> _data = new Map<String, Object>();
 
   /**
@@ skipping 149 matching lines @@
   static _ConsoleVariables _consoleTempVariables = new _ConsoleVariables();
 
   /**
    * Header passed in from the Dartium Developer Tools when an expression is
    * evaluated in the console as opposed to the watch window or another context
    * that does not expect REPL support.
    */
   static const _CONSOLE_API_SUPPORT_HEADER =
       'with ((this && this.console && this.console._commandLineAPI) || {}) {\n';
 
+  static bool expectsConsoleApi(String expression) {
+    return expression.indexOf(_CONSOLE_API_SUPPORT_HEADER) == 0;;
+  }
+
   /**
    * Takes an [expression] and a list of [local] variable and returns an
    * expression for a closure with a body matching the original expression
    * where locals are passed in as arguments. Returns a list containing the
    * String expression for the closure and the list of arguments that should
    * be passed to it. The expression should then be evaluated using
    * Dart_EvaluateExpr which will generate a closure that should be invoked
    * with the list of arguments passed to this method.
    *
    * For example:
@@ skipping 24 matching lines @@
       // 'this' needs to be handled by calling Dart_EvaluateExpr with
       // 'this' as the target rather than by passing it as an argument.
       if (arg == 'this') return;
       if (args.isNotEmpty) {
         sb.write(", ");
       }
       sb.write("final $arg");
       args[arg] = value;
     }
 
-    if (expression.indexOf(_CONSOLE_API_SUPPORT_HEADER) == 0) {
+    if (expectsConsoleApi(expression)) {
       expression = expression.substring(expression.indexOf('\n') + 1);
       expression = expression.substring(0, expression.lastIndexOf('\n'));
 
       addArg("\$consoleVariables", _consoleTempVariables);
 
       // FIXME: use a real Dart tokenizer. The following regular expressions
       // only allow setting variables at the immediate start of the expression
       // to limit the number of edge cases we have to handle.
 
       // Match expressions that start with "var x"
@@ skipping 356 matching lines @@
   _scheduleImmediateHelper._schedule(callback);
 };
 
 get _pureIsolateScheduleImmediateClosure => ((void callback()) =>
   throw new UnimplementedError("scheduleMicrotask in background isolates "
                                "are not supported in the browser"));
 
 void _initializeCustomElement(Element e) {
   _Utils.initializeCustomElement(e);
 }