Revert of [es6] stage sticky regexps and RegExp.prototype.flags.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 79348cb7101e8f9b1b2713d014767b8e896ac9d5..edbe4ebab796354d6ed31cbc5cc3663123b51719 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -190,6 +190,7 @@
 // Features that are still work in progress (behind individual flags).
 #define HARMONY_INPROGRESS(V)                                         \
   V(harmony_modules, "harmony modules")                               \
+  V(harmony_regexps, "harmony regular expression extensions")         \
   V(harmony_proxies, "harmony proxies")                               \
   V(harmony_unicode_regexps, "harmony unicode regexps")               \
   V(harmony_tolength, "harmony ToLength")                             \
@@ -201,11 +202,10 @@
   V(harmony_simd, "harmony simd")
 
 // Features that are complete (but still behind --harmony/es-staging flag).
-#define HARMONY_STAGED(V)                                     \
-  V(harmony_regexps, "harmony regular expression extensions") \
-  V(harmony_tostring, "harmony toString")                     \
-  V(harmony_sloppy, "harmony features in sloppy mode")        \
-  V(harmony_sloppy_let, "harmony let in sloppy mode")         \
+#define HARMONY_STAGED(V)                              \
+  V(harmony_tostring, "harmony toString")              \
+  V(harmony_sloppy, "harmony features in sloppy mode") \
+  V(harmony_sloppy_let, "harmony let in sloppy mode")  \
   V(harmony_completion, "harmony completion value semantics")
 
 // Features that are shipping (turned on by default, but internal flag remains).