Make string juxtaposition combine properly with string interpolations.

frog/leg/typechecker.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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name() => "Type checker";
 
   static final bool LOG_FAILURES = false;
 
@@ skipping 473 matching lines @@
   }
 
   Type visitLiteralBool(LiteralBool node) {
     return boolType;
   }
 
   Type visitLiteralString(LiteralString node) {
     return stringType;
   }
 
-  Type visitLiteralStringJuxtaposition(LiteralStringJuxtaposition node) {
+  Type visitStringJuxtaposition(StringJuxtaposition node) {
+    analyze(node.first);
+    analyze(node.second);
     return stringType;
   }
 
   Type visitLiteralNull(LiteralNull node) {
     return types.dynamicType;
   }
 
   Type visitNewExpression(NewExpression node) {
     return analyze(node.send.selector);
   }
@@ skipping 188 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     fail(node);
   }
 
   visitTypedef(Typedef node) {
     fail(node);
   }
 }