Ship --harmony-regexp-exec

The Chrome Extensions code that was broken by this change the first time
it landed has been amended to deal appropriately with the ES2015
semantics in https://codereview.chromium.org/1864733002/.

BUG=v8:4602
LOG=y

Review URL: https://codereview.chromium.org/1857313003

Cr-Commit-Position: refs/heads/master@{#35279}

src/flag-definitions.h

@@ -204,7 +204,6 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
 
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                                    \
-  V(harmony_regexp_exec, "harmony RegExp exec override behavior")            \
   V(harmony_regexp_lookbehind, "harmony regexp lookbehind")                  \
   V(harmony_tailcalls, "harmony tail calls")                                 \
   V(harmony_object_values_entries, "harmony Object.values / Object.entries") \
@@ -219,6 +218,7 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
   V(harmony_instanceof, "harmony instanceof support")                 \
   V(harmony_iterator_close, "harmony iterator finalization")          \
   V(harmony_unicode_regexps, "harmony unicode regexps")               \
+  V(harmony_regexp_exec, "harmony RegExp exec override behavior")     \
   V(harmony_sloppy, "harmony features in sloppy mode")                \
   V(harmony_sloppy_let, "harmony let in sloppy mode")                 \
   V(harmony_sloppy_function, "harmony sloppy function block scoping") \

test/mjsunit/es6/regexp-flags.js

@@ -44,9 +44,11 @@ assertEquals(2, get_count);
 // Overridden flag getters affects the flags getter.
 assertEquals("gi", r3.flags);
 assertEquals(4, get_count);
-// Overridden flag getters do not affect the internal flags.
+// Overridden flag getters affect string.replace
+// TODO(adamk): Add more tests here once we've switched
+// to use [[OriginalFlags]] in more cases.
 assertEquals(expected, string.replace(r3, "X"));
-assertEquals(4, get_count);
+assertEquals(5, get_count);
 
 
 function testName(name) {