Make string juxtaposition combine properly with string interpolations.

frog/leg/compile_time_constants.dart

Index: frog/leg/compile_time_constants.dart
diff --git a/frog/leg/compile_time_constants.dart b/frog/leg/compile_time_constants.dart
index 5572019ca39e77777a8a8f1c8c0ed1d083c0f653..e2fb31236bb7a49e9b44d183bbd9caf7c23c3846 100644
--- a/frog/leg/compile_time_constants.dart
+++ b/frog/leg/compile_time_constants.dart
@@ -59,7 +59,7 @@ class PrimitiveConstant extends Constant {
   bool operator ==(var other) {
     if (other is !PrimitiveConstant) return false;
     PrimitiveConstant otherPrimitive = other;
-    // We use == instead of === so that DartStrings compare correctly. 
+    // We use == instead of === so that DartStrings compare correctly.
     return value == otherPrimitive.value;
   }
 
@@ -119,7 +119,7 @@ class IntConstant extends PrimitiveConstant {
           case "~/": return new IntConstant(value ~/ right);
           case "|": return new IntConstant(value | right);
           case "&": return new IntConstant(value & right);
-          case "^": return new IntConstant(value ^ right);        
+          case "^": return new IntConstant(value ^ right);
           case "<<":
             // TODO(floitsch): find a better way to guard against shifts to the
             // left.
@@ -171,7 +171,7 @@ class DoubleConstant extends PrimitiveConstant {
     } else if (value == -double.INFINITY) {
       buffer.add("(-1/0)");
     } else {
-      buffer.add("($value)");        
+      buffer.add("($value)");
     }
   }
 
@@ -269,7 +269,7 @@ class StringConstant extends PrimitiveConstant {
     if (other.isString() && op == "+") {
       StringConstant otherString = other;
       DartString right = otherString.value;
-      return new StringConstant(new ConsDartString(value, right));
+      return new StringConstant(new DartString.cons(value, right));
     }
     // Visit super in case the [op] was "==", "===", "!=" or "!===".
     return super.binaryFold(op, other);
@@ -295,7 +295,7 @@ class ListConstant extends ObjectConstant {
   int _hashCode;
 
   ListConstant(Type type, this.entries) : super(type) {
-    // TODO(floitsch): create a better hash. 
+    // TODO(floitsch): create a better hash.
     int hash = 0;
     for (Constant input in entries) hash ^= input.hashCode();
     _hashCode = hash;
@@ -342,7 +342,7 @@ class ConstructedConstant extends ObjectConstant {
 
   ConstructedConstant(Type type, this.fields) : super(type) {
     assert(type !== null);
-    // TODO(floitsch): create a better hash. 
+    // TODO(floitsch): create a better hash.
     int hash = 0;
     for (Constant field in fields) {
       hash ^= field.hashCode();
@@ -523,7 +523,7 @@ class ConstantHandler extends CompilerTask {
 
   StringBuffer writeJsCode(StringBuffer buffer, Constant value) {
     value.writeJsCode(buffer, this);
-    return buffer;    
+    return buffer;
   }
 
   StringBuffer writeJsCodeForVariable(StringBuffer buffer,
@@ -543,7 +543,7 @@ class ConstantHandler extends CompilerTask {
       String name = compiledConstants[constant];
       buffer.add("${compiler.namer.ISOLATE}.prototype.$name");
     } else {
-      writeJsCode(buffer, constant);      
+      writeJsCode(buffer, constant);
     }
     return buffer;
   }
@@ -629,11 +629,11 @@ class CompileTimeConstantEvaluator extends AbstractVisitor {
     // there.
     return node.value ? const BoolConstant(true) : const BoolConstant(false);
   }
-  
+
   Constant visitLiteralDouble(LiteralDouble node) {
     return new DoubleConstant(node.value);
   }
-  
+
   Constant visitLiteralInt(LiteralInt node) {
     return new IntConstant(node.value);
   }