Make sure to bind a method to its receiver if it is stored in a temporary.

pkg/compiler/lib/src/js/rewrite_async.dart

Index: pkg/compiler/lib/src/js/rewrite_async.dart
diff --git a/pkg/compiler/lib/src/js/rewrite_async.dart b/pkg/compiler/lib/src/js/rewrite_async.dart
index 1490ada8cc61d4082c436dbefdf0910dd5e23f9c..6d3e1589ebf2f3328f369b4354de7617c8ff9d79 100644
--- a/pkg/compiler/lib/src/js/rewrite_async.dart
+++ b/pkg/compiler/lib/src/js/rewrite_async.dart
@@ -399,11 +399,39 @@ abstract class AsyncRewriterBase extends js.NodeVisitor {
     // Note that RegExes, js.ArrayInitializer and js.ObjectInitializer are not
     // [js.Literal]s.
     if (result is js.Literal) return result;
+
+    js.Expression tempVar = useTempVar(allocateTempVar());
+    addStatement(js.js.statement('# = #;', [tempVar, result]));
+    return tempVar;
+  }
+
+
+  /// Like [_storeIfNecessary] but binds JavaScript `this` of the function if
+  /// the receiver is a [js.PropertyAccess].
+  /// This is necessary because we cannot translate `a.b()` to:
+  ///     temp = a.b;

[floitsch, 2015/03/06 16:32:15]

nit: make sure that this mark-downs right. (maybe needs a new line)

+  ///     temp();
+  /// This leaves `this` unbound in the call. Take care to bind a

[floitsch, 2015/03/06 16:32:15]

ditto here.

+  js.Expression _storeAndBindIfNecessary(js.Expression result) {
+    // Note that RegExes, js.ArrayInitializer and js.ObjectInitializer are not
+    // [js.Literal]s.
+    if (result is js.Literal) return result;
+    if (result is js.PropertyAccess) {
+      js.Expression tempVar = useTempVar(allocateTempVar());
+      addStatement(js.js.statement('# = #', [tempVar, result.receiver]));
+      addStatement(js.js.statement('# = #.#.bind(#)', [
+        tempVar, tempVar, result.selector, tempVar
+      ]));
+      return tempVar;
+    }
+
     js.Expression tempVar = useTempVar(allocateTempVar());
     addStatement(js.js.statement('# = #;', [tempVar, result]));
     return tempVar;
   }
 
+  // TODO(sigurdm): This is obsolete - all calls use store: false. Replace with
+  // visitExpression(node);
   withExpression(js.Expression node, fn(js.Expression result), {bool store}) {
     int oldTempVarIndex = currentTempVarIndex;
     js.Expression visited = visitExpression(node);
@@ -415,6 +443,19 @@ abstract class AsyncRewriterBase extends js.NodeVisitor {
     return result;
   }
 
+  withExpressionBinding(js.Expression node,
+                        fn(js.Expression result), {bool store}) {
+    int oldTempVarIndex = currentTempVarIndex;
+    js.Expression visited = visitExpression(node);
+    if (store) {
+      visited = _storeAndBindIfNecessary(visited);
+    }
+    var result = fn(visited);
+    currentTempVarIndex = oldTempVarIndex;
+    return result;
+  }
+
+
   /// Calls [fn] with the value of evaluating [node1] and [node2].
   ///
   /// If `shouldTransform(node2)` the first expression is stored in a temporary
@@ -804,7 +845,7 @@ abstract class AsyncRewriterBase extends js.NodeVisitor {
   @override
   js.Expression visitCall(js.Call node) {
     bool storeTarget = node.arguments.any(shouldTransform);
-    return withExpression(node.target, (target) {
+    return withExpressionBinding(node.target, (target) {
       return withExpressions(node.arguments, (List<js.Expression> arguments) {
         return new js.Call(target, arguments);
       });
@@ -919,7 +960,8 @@ abstract class AsyncRewriterBase extends js.NodeVisitor {
       bool oldInsideUntranslatedBreakable = insideUntranslatedBreakable;
       insideUntranslatedBreakable = true;
       withExpression(node.condition, (js.Expression condition) {
-        addStatement(js.js.statement('do {#} while (#)', [node.body, condition]));
+        addStatement(js.js.statement('do {#} while (#)',
+                                     [node.body, condition]));
       }, store: false);
       insideUntranslatedBreakable = oldInsideUntranslatedBreakable;
       return;
@@ -1147,7 +1189,7 @@ abstract class AsyncRewriterBase extends js.NodeVisitor {
   @override
   js.Expression visitNew(js.New node) {
     bool storeTarget = node.arguments.any(shouldTransform);
-    return withExpression(node.target, (target) {
+    return withExpressionBinding(node.target, (target) {
       return withExpressions(node.arguments, (List<js.Expression> arguments) {
         return new js.New(target, arguments);
       });
@@ -1775,7 +1817,8 @@ class SyncStarRewriter extends AsyncRewriterBase {
                         js.VariableDeclarationList variableDeclarations) {
     // Each iterator invocation on the iterable should work on its own copy of
     // the parameters.
-    // TODO(sigurdm): We only need to do this copying for parameters that are mutated.
+    // TODO(sigurdm): We only need to do this copying for parameters that are
+    // mutated.
     List<js.VariableInitialization> declarations =
         new List<js.VariableInitialization>();
     List<js.Parameter> renamedParameters = new List<js.Parameter>();