Make string juxtaposition combine properly with string interpolations.

frog/leg/compile_time_constants.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 Constant implements Hashable {
   const Constant();
 
   bool isNull() => false;
   bool isBool() => false;
   bool isTrue() => false;
@@ skipping 751 matching lines @@
   }
 
   Constant visitLiteralNull(LiteralNull node) {
     return new NullConstant();
   }
 
   Constant visitLiteralString(LiteralString node) {
     return new StringConstant(node.dartString);
   }
 
+  Constant visitStringJuxtaposition(StringJuxtaposition node) {
+    if (!node.isInterpolation) {
+      return new StringConstant(node.dartString);
+    }
+    return super.visitStringJuxtaposition(node);
+  }
+
   // TODO(floitsch): provide better error-messages.
   Constant visitSend(Send send) {
     Element element = elements[send];
     if (Elements.isStaticOrTopLevelField(element)) {
       if (element.modifiers === null ||
           !element.modifiers.isFinal()) {
         error(send);
       }
       return constantHandler.compileVariable(element);
     } else if (send.isPrefix) {
@@ skipping 221 matching lines @@
                           initializerEvaluator,
                           constructorElements,
                           constructorDefinitions,
                           fieldValues);
     }
     List<Constant> jsNewArguments =
         buildJsNewArguments(classElement, fieldValues);
 
     compiler.registerInstantiatedClass(classElement);
     // TODO(floitsch): take generic types into account.
-    Type type = classElement.computeType(compiler);      
+    Type type = classElement.computeType(compiler);
     Constant constant = new ConstructedConstant(type, jsNewArguments);
     constantHandler.registerCompileTimeConstant(constant);
     return constant;
   }
 
   error(Node node) {
     // TODO(floitsch): get the list of constants that are currently compiled
     // and present some kind of stack-trace.
     MessageKind kind = MessageKind.NOT_A_COMPILE_TIME_CONSTANT;
     compiler.reportError(node, new CompileTimeConstantError(kind, const []));
   }
 }