Improve decoding of JS TypeError.

dart/sdk/lib/_internal/compiler/implementation/lib/string_helper.dart

Index: dart/sdk/lib/_internal/compiler/implementation/lib/string_helper.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/lib/string_helper.dart b/dart/sdk/lib/_internal/compiler/implementation/lib/string_helper.dart
index 6e4dccfb2b057aceb67c705d27ef2c06a2dfab45..58a6267b0b938ae2effe5c78a93391f4722e6de1 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/lib/string_helper.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/lib/string_helper.dart
@@ -77,7 +77,9 @@ stringReplaceJS(receiver, replacer, to) {
   return JS('String', r'#.replace(#, #)', receiver, replacer, to);
 }
 
-final RegExp quoteRegExp = new JSSyntaxRegExp(r'[-[\]{}()*+?.,\\^$|#\s]');
+const String ESCAPE_REGEXP = r'[-[\]{}()*+?.,\\^$|]';
+
+final RegExp quoteRegExp = new JSSyntaxRegExp(ESCAPE_REGEXP);
 
 stringReplaceAllUnchecked(receiver, from, to) {
   checkString(to);
@@ -86,14 +88,12 @@ stringReplaceAllUnchecked(receiver, from, to) {
       if (receiver == "") {
         return to;
       } else {
-        StringBuffer result = new StringBuffer();
+        String result = to;
         int length = receiver.length;
-        result.add(to);
         for (int i = 0; i < length; i++) {
-          result.add(receiver[i]);
-          result.add(to);
+          result = '$result${receiver[i]}$to';
         }
-        return result.toString();
+        return result;
       }
     } else {
       var quoter = regExpMakeNative(quoteRegExp, global: true);
@@ -125,25 +125,24 @@ stringReplaceAllFuncUnchecked(receiver, pattern, onMatch, onNonMatch) {
     return stringReplaceAllStringFuncUnchecked(receiver, pattern,
                                                onMatch, onNonMatch);
   }
-  StringBuffer buffer = new StringBuffer();
+  String result = '';
   int startIndex = 0;
   for (Match match in pattern.allMatches(receiver)) {
-    buffer.add(onNonMatch(receiver.substring(startIndex, match.start)));
-    buffer.add(onMatch(match));
-    startIndex = match.end;
+    result =
+        '$result'
+        '${onNonMatch(receiver.substring(startIndex, match.start))}'
+        '${onMatch(match)}';
   }
-  buffer.add(onNonMatch(receiver.substring(startIndex)));
-  return buffer.toString();
+  return '$result${onNonMatch(receiver.substring(startIndex))}';
 }
 
 stringReplaceAllEmptyFuncUnchecked(receiver, onMatch, onNonMatch) {
   // Pattern is the empty string.
-  StringBuffer buffer = new StringBuffer();
   int length = receiver.length;
   int i = 0;
-  buffer.add(onNonMatch(""));
+  String result = '${onNonMatch("")}';
   while (i < length) {
-    buffer.add(onMatch(new StringMatch(i, receiver, "")));
+    result = '$result${onMatch(new StringMatch(i, receiver, ""))}';
     // Special case to avoid splitting a surrogate pair.
     int code = receiver.charCodeAt(i);
     if ((code & ~0x3FF) == 0xD800 && length > i + 1) {
@@ -151,17 +150,17 @@ stringReplaceAllEmptyFuncUnchecked(receiver, onMatch, onNonMatch) {
       code = receiver.charCodeAt(i + 1);
       if ((code & ~0x3FF) == 0xDC00) {
         // Matching trailing surrogate.
-        buffer.add(onNonMatch(receiver.substring(i, i + 2)));
+        result = '$result${onNonMatch(receiver.substring(i, i + 2))}';
         i += 2;
         continue;
       }
     }
-    buffer.add(onNonMatch(receiver[i]));
+    result = '$result${onNonMatch(receiver[i])}';
     i++;
   }
-  buffer.add(onMatch(new StringMatch(i, receiver, "")));
-  buffer.add(onNonMatch(""));
-  return buffer.toString();
+  return
+      '$result${onMatch(new StringMatch(i, receiver, ""))}'
+      '${onNonMatch("")}';
 }
 
 stringReplaceAllStringFuncUnchecked(receiver, pattern, onMatch, onNonMatch) {
@@ -170,19 +169,19 @@ stringReplaceAllStringFuncUnchecked(receiver, pattern, onMatch, onNonMatch) {
     return stringReplaceAllEmptyFuncUnchecked(receiver, onMatch, onNonMatch);
   }
   int length = receiver.length;
-  StringBuffer buffer = new StringBuffer();
+  String result = '';
   int startIndex = 0;
   while (startIndex < length) {
     int position = receiver.indexOf(pattern, startIndex);
     if (position == -1) {
       break;
     }
-    buffer.add(onNonMatch(receiver.substring(startIndex, position)));
-    buffer.add(onMatch(new StringMatch(position, receiver, pattern)));
+    result =
+        '$result${onNonMatch(receiver.substring(startIndex, position))}'
+        '${onMatch(new StringMatch(position, receiver, pattern))}';
     startIndex = position + patternLength;
   }
-  buffer.add(onNonMatch(receiver.substring(startIndex)));
-  return buffer.toString();
+  return '$result${onNonMatch(receiver.substring(startIndex))}';
 }