[regexp] simplify unicode flag check.

It's sufficient to check for --harmony-unicode-regexps when parsing the
regexp flags from string.

R=neis@chromium.org

Review URL: https://codereview.chromium.org/1567413002

Cr-Commit-Position: refs/heads/master@{#33178}

src/regexp/regexp-parser.cc

@@ -343,7 +343,7 @@ RegExpTree* RegExpParser::ParseDisjunction() {
               // escaped,
               // no other identity escapes are allowed. If the 'u' flag is not
               // present, all identity escapes are allowed.
-              if (!FLAG_harmony_unicode_regexps || !unicode_) {
+              if (!unicode_) {
                 builder->AddCharacter(first_digit);
                 Advance(2);
               } else {
@@ -404,7 +404,7 @@ RegExpTree* RegExpParser::ParseDisjunction() {
             uc32 value;
             if (ParseHexEscape(2, &value)) {
               builder->AddCharacter(value);
-            } else if (!FLAG_harmony_unicode_regexps || !unicode_) {
+            } else if (!unicode_) {
               builder->AddCharacter('x');
             } else {
               // If the 'u' flag is present, invalid escapes are not treated as
@@ -418,7 +418,7 @@ RegExpTree* RegExpParser::ParseDisjunction() {
             uc32 value;
             if (ParseUnicodeEscape(&value)) {
               builder->AddCharacter(value);
-            } else if (!FLAG_harmony_unicode_regexps || !unicode_) {
+            } else if (!unicode_) {
               builder->AddCharacter('u');
             } else {
               // If the 'u' flag is present, invalid escapes are not treated as
@@ -434,8 +434,7 @@ RegExpTree* RegExpParser::ParseDisjunction() {
             // other identity escapes are allowed. If the 'u' flag is not
             // present,
             // all identity escapes are allowed.
-            if (!FLAG_harmony_unicode_regexps || !unicode_ ||
-                IsSyntaxCharacter(current())) {
+            if (!unicode_ || IsSyntaxCharacter(current())) {
               builder->AddCharacter(current());
               Advance();
             } else {
@@ -736,7 +735,7 @@ bool RegExpParser::ParseUnicodeEscape(uc32* value) {
   // Accept both \uxxxx and \u{xxxxxx} (if harmony unicode escapes are
   // allowed). In the latter case, the number of hex digits between { } is
   // arbitrary. \ and u have already been read.
-  if (current() == '{' && FLAG_harmony_unicode_regexps && unicode_) {
+  if (current() == '{' && unicode_) {
     int start = position();
     Advance();
     if (ParseUnlimitedLengthHexNumber(0x10ffff, value)) {
@@ -831,7 +830,7 @@ uc32 RegExpParser::ParseClassCharacterEscape() {
       if (ParseHexEscape(2, &value)) {
         return value;
       }
-      if (!FLAG_harmony_unicode_regexps || !unicode_) {
+      if (!unicode_) {
         // If \x is not followed by a two-digit hexadecimal, treat it
         // as an identity escape.
         return 'x';
@@ -847,7 +846,7 @@ uc32 RegExpParser::ParseClassCharacterEscape() {
       if (ParseUnicodeEscape(&value)) {
         return value;
       }
-      if (!FLAG_harmony_unicode_regexps || !unicode_) {
+      if (!unicode_) {
         return 'u';
       }
       // If the 'u' flag is present, invalid escapes are not treated as
@@ -860,8 +859,7 @@ uc32 RegExpParser::ParseClassCharacterEscape() {
       // If the 'u' flag is present, only syntax characters can be escaped, no
       // other identity escapes are allowed. If the 'u' flag is not present, all
       // identity escapes are allowed.
-      if (!FLAG_harmony_unicode_regexps || !unicode_ ||
-          IsSyntaxCharacter(result)) {
+      if (!unicode_ || IsSyntaxCharacter(result)) {
         Advance();
         return result;
       }