Ship ES2015 iterator finalization

This patch moves iterator finalization (calling .return() when a
for-of loop exits early) to shipping. The only part of this feature
which is currently known to be missing is destructuring--.return()
should be also be called when destructuring with an array which
does not end in a rest pattern, but it currently does not. The rest
of this feature, including calling .return() from certain builtins,
is implemented.

R=adamk
BUG=v8:3566
LOG=Y

Review URL: https://codereview.chromium.org/1738463003

Cr-Commit-Position: refs/heads/master@{#34307}

src/flag-definitions.h

@@ -221,7 +221,6 @@ DEFINE_IMPLICATION(es_staging, harmony_tailcalls)
 #define HARMONY_STAGED(V)                                     \
   V(harmony_function_name, "harmony Function name inference") \
   V(harmony_regexp_lookbehind, "harmony regexp lookbehind")   \
-  V(harmony_iterator_close, "harmony iterator finalization")  \
   V(harmony_instanceof, "harmony instanceof support")
 
 // Features that are shipping (turned on by default, but internal flag remains).
@@ -229,6 +228,7 @@ DEFINE_IMPLICATION(es_staging, harmony_tailcalls)
   V(harmony_default_parameters, "harmony default parameters")             \
   V(harmony_destructuring_assignment, "harmony destructuring assignment") \
   V(harmony_destructuring_bind, "harmony destructuring bind")             \
+  V(harmony_iterator_close, "harmony iterator finalization")              \
   V(harmony_tostring, "harmony toString")                                 \
   V(harmony_regexps, "harmony regular expression extensions")             \
   V(harmony_unicode_regexps, "harmony unicode regexps")                   \

test/cctest/cctest.status

@@ -93,6 +93,10 @@
   'test-api/StrongModeAccessCheckAllowed': [FAIL],
   'test-api/StrongModeAccessCheckBlocked': [FAIL],
 
+  # Iterator finalization was implemented, which changed the bytecode
+  # generated from for-of loops
+  'test-bytecode-generator/ForOf': [FAIL],
+
   ##############################################################################
   # TurboFan compiler failures.
 

test/mjsunit/harmony/regress/regress-4658.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-do-expressions
+// Flags: --harmony-do-expressions --noharmony-iterator-close
 
 (function testWithSimpleLoopVariable() {
   var f = (x, y = (do { var s=0; for (var e of x) s += e; s; })) => y*(y+1);