Revert of [es6] ship Object.assign (patchset #2 id:20001 of...

Revert of [es6] ship Object.assign (patchset #2 id:20001 of https://codereview.chromium.org/1191003003/)

Reason for revert:
Seems to break asan somehow

Original issue's description:
> [es6] ship Object.assign
>
> BUG=v8:4007
> LOG=N
> R=rossberg@chromium.org, arv@chromium.org
> CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
>
> Committed: https://crrev.com/12e194860a56d47a10d89ae34761a4af6b6166bb
> Cr-Commit-Position: refs/heads/master@{#29118}

TBR=arv@chromium.org,dslomov@chromium.org,rossberg@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4007

Review URL: https://codereview.chromium.org/1191593005

Cr-Commit-Position: refs/heads/master@{#29124}

src/flag-definitions.h

@@ -201,6 +201,7 @@ DEFINE_IMPLICATION(es_staging, harmony)
   V(harmony_arrays, "harmony array methods")                   \
   V(harmony_rest_parameters, "harmony rest parameters")        \
   V(harmony_spreadcalls, "harmony spread-calls")               \
+  V(harmony_object, "harmony Object methods")                  \
   V(harmony_spread_arrays, "harmony spread in array literals") \
   V(harmony_tostring, "harmony toString")
 
@@ -211,7 +212,6 @@ DEFINE_IMPLICATION(es_staging, harmony)
   V(harmony_computed_property_names, "harmony computed property names")    \
   V(harmony_object_literals, "harmony object literal extensions")          \
   V(harmony_unicode, "harmony unicode escapes")                            \
-  V(harmony_object, "harmony Object methods")
 
 // Once a shipping feature has proved stable in the wild, it will be dropped
 // from HARMONY_SHIPPING, all occurrences of the FLAG_ variable are removed,

test/webkit/fast/js/Object-getOwnPropertyNames-expected.txt

@@ -44,7 +44,7 @@ PASS getSortedOwnPropertyNames(decodeURI) is ['length', 'name']
 PASS getSortedOwnPropertyNames(decodeURIComponent) is ['length', 'name']
 PASS getSortedOwnPropertyNames(encodeURI) is ['length', 'name']
 PASS getSortedOwnPropertyNames(encodeURIComponent) is ['length', 'name']
-PASS getSortedOwnPropertyNames(Object) is ['arguments', 'assign', 'caller', 'create', 'defineProperties', 'defineProperty', 'deliverChangeRecords', 'freeze', 'getNotifier', 'getOwnPropertyDescriptor', 'getOwnPropertyNames', 'getOwnPropertySymbols', 'getPrototypeOf', 'is', 'isExtensible', 'isFrozen', 'isSealed', 'keys', 'length', 'name', 'observe', 'preventExtensions', 'prototype', 'seal', 'setPrototypeOf', 'unobserve']
+PASS getSortedOwnPropertyNames(Object) is ['arguments', 'caller', 'create', 'defineProperties', 'defineProperty', 'deliverChangeRecords', 'freeze', 'getNotifier', 'getOwnPropertyDescriptor', 'getOwnPropertyNames', 'getOwnPropertySymbols', 'getPrototypeOf', 'is', 'isExtensible', 'isFrozen', 'isSealed', 'keys', 'length', 'name', 'observe', 'preventExtensions', 'prototype', 'seal', 'setPrototypeOf', 'unobserve']
 PASS getSortedOwnPropertyNames(Object.prototype) is ['__defineGetter__', '__defineSetter__', '__lookupGetter__', '__lookupSetter__', '__proto__', 'constructor', 'hasOwnProperty', 'isPrototypeOf', 'propertyIsEnumerable', 'toLocaleString', 'toString', 'valueOf']
 PASS getSortedOwnPropertyNames(Function) is ['arguments', 'caller', 'length', 'name', 'prototype']
 PASS getSortedOwnPropertyNames(Function.prototype) is ['apply', 'arguments', 'bind', 'call', 'caller', 'constructor', 'length', 'name', 'toString']

test/webkit/fast/js/Object-getOwnPropertyNames.js

@@ -71,7 +71,7 @@ var expectedPropertyNamesSet = {
     "encodeURI": "['length', 'name']",
     "encodeURIComponent": "['length', 'name']",
 // Built-in ECMA objects
-    "Object": "['arguments', 'assign', 'caller', 'create', 'defineProperties', 'defineProperty', 'deliverChangeRecords', 'freeze', 'getNotifier', 'getOwnPropertyDescriptor', 'getOwnPropertyNames', 'getOwnPropertySymbols', 'getPrototypeOf', 'is', 'isExtensible', 'isFrozen', 'isSealed', 'keys', 'length', 'name', 'observe', 'preventExtensions', 'prototype', 'seal', 'setPrototypeOf', 'unobserve']",
+    "Object": "['arguments', 'caller', 'create', 'defineProperties', 'defineProperty', 'deliverChangeRecords', 'freeze', 'getNotifier', 'getOwnPropertyDescriptor', 'getOwnPropertyNames', 'getOwnPropertySymbols', 'getPrototypeOf', 'is', 'isExtensible', 'isFrozen', 'isSealed', 'keys', 'length', 'name', 'observe', 'preventExtensions', 'prototype', 'seal', 'setPrototypeOf', 'unobserve']",
     "Object.prototype": "['__defineGetter__', '__defineSetter__', '__lookupGetter__', '__lookupSetter__', '__proto__', 'constructor', 'hasOwnProperty', 'isPrototypeOf', 'propertyIsEnumerable', 'toLocaleString', 'toString', 'valueOf']",
     "Function": "['arguments', 'caller', 'length', 'name', 'prototype']",
     "Function.prototype": "['apply', 'arguments', 'bind', 'call', 'caller', 'constructor', 'length', 'name', 'toString']",