Don't put parenthesis to LiteralExpression (ie foreign expressions) when the expression starts a st…

lib/compiler/implementation/js/printer.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 Printer implements NodeVisitor {
   final bool shouldCompressOutput = false;
   leg.Compiler compiler;
   var positionElement;
   leg.CodeBuffer outBuffer;
   int indentLevel = 0;
@@ skipping 19 matching lines @@
     assert(lastAddedString.length != "");
     return lastAddedString.charCodeAt(lastAddedString.length - 1);
   }
 
   void out(String str) {
     if (str != "") {
       outBuffer.add(str);
       lastAddedString = str;
     }
   }
+
   void outLn(String str) {
     out(str);
     lineOut();
   }
+
   void outIndent(String str) { indent(); out(str); }
   void outIndentLn(String str) { indent(); outLn(str); }
   void indent() {
     if (!shouldCompressOutput) {
       for (int i = 0; i < indentLevel; i++) out("  ");
     }
   }
 
   void recordSourcePosition(var position) {
     if (position != null) {
@@ skipping 691 matching lines @@
   }
 
   visitLiteralExpression(LiteralExpression node) {
     String template = node.template;
     List<Expression> inputs = node.inputs;
 
     List<String> parts = template.split('#');
     if (parts.length != inputs.length + 1) {
       compiler.internalError('Wrong number of arguments for JS: $template');
     }
-    out("(");
+    // Save [atStatementBegin] because visiting the parts might change it.
+    bool beginStatement = atStatementBegin;
+    if (!beginStatement) out("(");
     out(parts[0]);
     for (int i = 0; i < inputs.length; i++) {
       visit(inputs[i]);
       out(parts[i + 1]);
     }
-    out(")");
+    if (!beginStatement) out(")");
   }
 
   visitLiteralStatement(LiteralStatement node) {
     outLn(node.code);
   }
 }
 
 /**
  * Returns true, if the given node must be wrapped into braces when used
  * as then-statement in an [If] that has an else branch.
@@ skipping 44 matching lines @@
 }
 
 
 leg.CodeBuffer prettyPrint(Node node,
                            leg.Compiler compiler,
                            Dynamic positionElement) {
   Printer printer = new Printer(compiler, positionElement);
   printer.visit(node);
   return printer.outBuffer;
 }