fix a few more codegen issues:

lib/src/js/builder.dart

 // Copyright (c) 2013, 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.
 
 // Utilities for building JS ASTs at runtime.  Contains a builder class
 // and a parser that parses part of the language.
 
 part of js_ast;
 
 
@@ skipping 280 matching lines @@
   }
 
   Template statementTemplateYielding(Node ast) {
     return new Template.withStatementResult(ast);
   }
 
   /// Creates a literal js string from [value].
   LiteralString escapedString(String value, [String quote = '"']) {
    // Start by escaping the backslashes.
     String escaped = value.replaceAll('\\', '\\\\');
-    // Do not escape unicode characters and ' because they are allowed in the
-    // string literal anyway.
-    var re = new RegExp('\n|\r|$quote|\b|\f|\t|\v');
+
+    // http://www.ecma-international.org/ecma-262/6.0/#sec-literals-string-literals
+    // > All code points may appear literally in a string literal except for the
+    // > closing quote code points, U+005C (REVERSE SOLIDUS),
+    // > U+000D (CARRIAGE RETURN), U+2028 (LINE SEPARATOR),
+    // > U+2029 (PARAGRAPH SEPARATOR), and U+000A (LINE FEED).
+    var re = new RegExp('\n|\r|$quote|\b|\f|\t|\v|\u2028|\u2029');
     escaped = escaped.replaceAllMapped(re, (m) {
       switch (m.group(0)) {
         case "\n" : return r"\n";
         case "\r" : return r"\r";
+        case "\u2028": return r"\u2028";
+        case "\u2029": return r"\u2029";
         // Quotes are only replaced if they conflict with the containing quote
         case '"':   return r'\"';
         case "'":   return r"\'";
         case "`":   return r"\`";
+        // TODO(jmesserly): these don't need to be escaped for correctness,
+        // but they are conventionally escaped.
         case "\b" : return r"\b";
         case "\t" : return r"\t";
         case "\f" : return r"\f";
         case "\v" : return r"\v";
       }
     });
     LiteralString result = new LiteralString('$quote$escaped$quote');
     // We don't escape quotes of a different style under the assumption that the
     // string is wrapped into quotes. Verify that assumption.
     assert(result.value.codeUnitAt(0) == quote.codeUnitAt(0));
@@ skipping 1246 matching lines @@
       expectCategory(RSQUARE);
       return expr;
     } else if (acceptCategory(HASH)) {
       return parseInterpolatedExpression();
     } else {
       error('Expected property name');
       return null;
     }
   }
 }