Further ES2015 RegExp spec compliance fixes

src/js/regexp.js

Index: src/js/regexp.js
diff --git a/src/js/regexp.js b/src/js/regexp.js
index fc5e0f54b8180945ef79dbb5be755f6387246878..d39771e9e329981871be76e825e2327059e6d145 100644
--- a/src/js/regexp.js
+++ b/src/js/regexp.js
@@ -194,8 +194,8 @@ function RegExpSubclassExecJS(string) {
   // algorithm, step 4) even if the value is discarded for non-global RegExps.
   var i = TO_LENGTH(lastIndex);
 
-  var global = TO_BOOLEAN(this.global);
-  var sticky = TO_BOOLEAN(this.sticky);
+  var global = TO_BOOLEAN(REGEXP_GLOBAL(this));
+  var sticky = TO_BOOLEAN(REGEXP_STICKY(this));
   var updateLastIndex = global || sticky;
   if (updateLastIndex) {
     if (i > string.length) {
@@ -370,27 +370,14 @@ function TrimRegExp(regexp) {
 
 
 function RegExpToString() {
-  if (!IS_REGEXP(this)) {
-    // RegExp.prototype.toString() returns '/(?:)/' as a compatibility fix;
-    // a UseCounter is incremented to track it.
-    // TODO(littledan): Remove this workaround or standardize it
-    if (this === GlobalRegExpPrototype) {
-      %IncrementUseCounter(kRegExpPrototypeToString);
-      return '/(?:)/';
-    }
-    if (!IS_RECEIVER(this)) {
-      throw MakeTypeError(
-          kIncompatibleMethodReceiver, 'RegExp.prototype.toString', this);
-    }
-    return '/' + TO_STRING(this.source) + '/' + TO_STRING(this.flags);
+  if (!IS_RECEIVER(this)) {
+    throw MakeTypeError(
+        kIncompatibleMethodReceiver, 'RegExp.prototype.toString', this);
   }
-  var result = '/' + REGEXP_SOURCE(this) + '/';
-  if (REGEXP_GLOBAL(this)) result += 'g';
-  if (REGEXP_IGNORE_CASE(this)) result += 'i';
-  if (REGEXP_MULTILINE(this)) result += 'm';
-  if (REGEXP_UNICODE(this)) result += 'u';
-  if (REGEXP_STICKY(this)) result += 'y';
-  return result;
+  if (this === GlobalRegExpPrototype) {
+    %IncrementUseCounter(kRegExpPrototypeToString);
+  }
+  return '/' + TO_STRING(this.source) + '/' + TO_STRING(this.flags);
 }
 
 
@@ -1126,7 +1113,7 @@ function RegExpGetSource() {
     // TODO(littledan): Remove this RegExp compat workaround
     if (this === GlobalRegExpPrototype) {
       %IncrementUseCounter(kRegExpPrototypeSourceGetter);
-      return UNDEFINED;
+      return "(?:)";
     }
     throw MakeTypeError(kRegExpNonRegExp, "RegExp.prototype.source");
   }