Refactor rewrite_async

tests/compiler/dart2js/async_await_js_transform_test.dart

 // Copyright (c) 2015, 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.
 
 import "package:expect/expect.dart";
 import "package:compiler/src/js/js.dart";
 import "package:compiler/src/js/rewrite_async.dart";
 
 import "backend_dart/dart_printer_test.dart" show PrintDiagnosticListener;
 
 void testTransform(String source, String expected) {
   Fun fun = js(source);
   Fun rewritten = new AsyncRewriter(
       null, // The diagnostic helper should not be used in these tests.
       null,
       asyncHelper: new VariableUse("thenHelper"),
       newCompleter: new VariableUse("Completer"),
-      endOfIteration: new VariableUse("endOfIteration"),
-      newIterable: new VariableUse("Iterator"),
       safeVariableName: (String name) => "__$name").rewrite(fun);
 
   JavaScriptPrintingOptions options = new JavaScriptPrintingOptions();
   SimpleJavaScriptPrintingContext context =
       new SimpleJavaScriptPrintingContext();
   Printer printer = new Printer(options, context);
   printer.visit(rewritten);
   Expect.stringEquals(expected, context.getText());
 }
 
@@ skipping 47 matching lines @@
           continue; // Continue from finally with pending finally.
           return 2; // Return from finally with pending finally.
         }
       }
     } finally {
       return 3; // Return from finally with no pending finally.
     }
     return 4;
   }""", """
 function(b) {
-  var __goto = 0, __completer = new Completer(), __handler = 2, __currentError, __next, __returnValue, __helper;
+  var __goto = 0, __completer = new Completer(), __returnValue, __handler = 2, __currentError, __next, __helper;
   function __body(__errorCode, __result) {
     if (__errorCode === 1) {
       __currentError = __result;
       __goto = __handler;
     }
     while (true)
       __outer1:
         switch (__goto) {
           case 0:
             // Function start
@@ skipping 437 matching lines @@
       break;
     if (!foo(i)) { // If with no else and await in body.
       await foo();
       return;
     }
     print(await(foo(i)));
   } 
 }
 """, """
 function(g) {
-  var __goto = 0, __completer = new Completer(), __handler = 2, __currentError, __returnValue, i, __temp1;
+  var __goto = 0, __completer = new Completer(), __returnValue, __handler = 2, __currentError, i, __temp1;
   function __body(__errorCode, __result) {
     if (__errorCode === 1) {
       __currentError = __result;
       __goto = __handler;
     }
     while (true)
       switch (__goto) {
         case 0:
           // Function start
           i = 0;
@@ skipping 145 matching lines @@
       x = c ? await fooError(error) : fooError(error);
     } catch (error) { // nested error handler with overlapping name
       y.x = foo(error);
     } finally {
       foo(x);
     }
   }
 }
 """, """
 function(c, i) {
-  var __goto = 0, __completer = new Completer(), __handler = 1, __currentError, __next, x, y, __error1, __error2;
+  var __goto = 0, __completer = new Completer(), __handler = 1, __currentError, __next, x, y, __error, __error1;
   function __body(__errorCode, __result) {
     if (__errorCode === 1) {
       __currentError = __result;
       __goto = __handler;
     }
     while (true)
       switch (__goto) {
         case 0:
           // Function start
           __handler = 3;
@@ skipping 15 matching lines @@
           // join
           x = __result;
           y = {};
           __handler = 1;
           // goto after finally
           __goto = 5;
           break;
         case 3:
           // catch
           __handler = 2;
-          __error1 = __currentError;
+          __error = __currentError;
           __handler = 11;
           __goto = c ? 14 : 16;
           break;
         case 14:
           // then
           __goto = 17;
-          return thenHelper(fooError(__error1), __body, __completer);
+          return thenHelper(fooError(__error), __body, __completer);
         case 17:
           // returning from await.
           // goto join
           __goto = 15;
           break;
         case 16:
           // else
-          __result = fooError(__error1);
+          __result = fooError(__error);
         case 15:
           // join
           x = __result;
           __next = [13];
           // goto finally
           __goto = 12;
           break;
         case 11:
           // catch
           __handler = 10;
-          __error2 = __currentError;
-          y.x = foo(__error2);
+          __error1 = __currentError;
+          y.x = foo(__error1);
           __next = [13];
           // goto finally
           __goto = 12;
           break;
         case 10:
           // uncaught
           __next = [2];
         case 12:
           // finally
           __handler = 2;
@@ skipping 109 matching lines @@
           continue;
         }
       default: // defaul case
         break lab; // break to label
       }
       foo();
     }
   }
 }""", """
 function(x, y, k) {
-  var __goto = 0, __completer = new Completer(), __handler = 2, __currentError, __returnValue, __temp1;
+  var __goto = 0, __completer = new Completer(), __returnValue, __handler = 2, __currentError, __temp1;
   function __body(__errorCode, __result) {
     if (__errorCode === 1) {
       __currentError = __result;
       __goto = __handler;
     }
     while (true)
       switch (__goto) {
         case 0:
           // Function start
         case 3:
@@ skipping 94 matching lines @@
           // return
           return thenHelper(__returnValue, 0, __completer, null);
         case 2:
           // rethrow
           return thenHelper(__currentError, 1, __completer);
       }
   }
   return thenHelper(null, __body, __completer, null);
 }""");
 }