Ship --harmony-regexp-exec

There are still spec compliance fixes to be made, but this patch
turns the flag to shipping to make sure we get more canary coverage
and performance data from the bots.

BUG=v8:4602
LOG=y

Review URL: https://codereview.chromium.org/1847103002

Cr-Commit-Position: refs/heads/master@{#35181}

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) {