Revert of Ship String.prototype.pad{Start,End} (patchset #2 id:20001 of...

Revert of Ship String.prototype.pad{Start,End} (patchset #2 id:20001 of https://codereview.chromium.org/2591853002/ )

Reason for revert:
Fails on gcstress bot (mjsunit/regress/regress-trap-allocation-memento.js)

Original issue's description:
> Ship String.prototype.pad{Start,End}
>
> BUG=v8:4954
> CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
>
> Review-Url: https://codereview.chromium.org/2591853002
> Cr-Commit-Position: refs/heads/master@{#41873}
> Committed: https://chromium.googlesource.com/v8/v8/+/07277202cf136e70c147e2f000e48964332bb01c

TBR=caitp@igalia.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4954

Review-Url: https://codereview.chromium.org/2588423003
Cr-Commit-Position: refs/heads/master@{#41874}

src/flag-definitions.h

@@ -210,7 +210,8 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
     "harmony restrictions on generator declarations")       \
   V(harmony_tailcalls, "harmony tail calls")                \
   V(harmony_trailing_commas,                                \
-    "harmony trailing commas in function parameter lists")
+    "harmony trailing commas in function parameter lists")  \
+  V(harmony_string_padding, "harmony String-padding methods")
 
 #ifdef V8_I18N_SUPPORT
 #define HARMONY_STAGED(V)                                          \
@@ -221,9 +222,7 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
 #endif
 
 // Features that are shipping (turned on by default, but internal flag remains).
-#define HARMONY_SHIPPING_BASE(V)                \
-  V(harmony_async_await, "harmony async-await") \
-  V(harmony_string_padding, "harmony String-padding methods")
+#define HARMONY_SHIPPING_BASE(V) V(harmony_async_await, "harmony async-await")
 
 #ifdef V8_I18N_SUPPORT
 #define HARMONY_SHIPPING(V) \