Register toString dynamic invocation in the presence of string interpolation.

lib/compiler/implementation/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   Type getType(TypeAnnotation annotation);
 }
 
@@ skipping 1426 matching lines @@
 
   visitConditional(Conditional node) {
     node.visitChildren(this);
   }
 
   visitStringInterpolation(StringInterpolation node) {
     node.visitChildren(this);
   }
 
   visitStringInterpolationPart(StringInterpolationPart node) {
+    world.registerDynamicInvocation(
+        const SourceString('toString'), Selector.INVOCATION_0);
     node.visitChildren(this);
   }
 
   visitBreakStatement(BreakStatement node) {
     TargetElement target;
     if (node.target === null) {
       target = statementScope.currentBreakTarget();
       if (target === null) {
         error(node, MessageKind.NO_BREAK_TARGET);
         return;
@@ skipping 852 matching lines @@
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element newElement) {
     throw "Cannot add an element in the top scope";
   }
   String toString() => '$element';
 }