Use a for-of loop in Array.from

If Array.from is passed an iterable, then it will copy the contents
to the newly created Array (or subclass). The iteration protocol here
includes calling IteratorClose if the loop is exited early due to an
exception thrown. This patch converts Array.from to use a for-of loop
rather than explicitly invoking the iteration protocol so that, when
IteratorClose is invoked on early for-of exit, then Array.from will
call IteratorClose in the appropriate case.

R=neis
LOG=Y
BUG=v8:4739

Review URL: https://codereview.chromium.org/1686433003

Cr-Commit-Position: refs/heads/master@{#33859}

src/js/array.js

@@ -1776,23 +1776,10 @@ function ArrayFrom(arrayLike, mapfn, receiver) {
 
   if (!IS_UNDEFINED(iterable)) {
     result = %IsConstructor(this) ? new this() : [];
-
-    var iterator = GetIterator(items, iterable);
-
     k = 0;
-    while (true) {
-      var next = iterator.next();
-
-      if (!IS_RECEIVER(next)) {
-        throw MakeTypeError(kIteratorResultNotAnObject, next);
-      }
 
-      if (next.done) {
-        result.length = k;
-        return result;
-      }
-
-      nextValue = next.value;
+    for (nextValue of
+         { [iteratorSymbol]() { return GetIterator(items, iterable) } }) {
       if (mapping) {
         mappedValue = %_Call(mapfn, receiver, nextValue, k);
       } else {
@@ -1801,6 +1788,8 @@ function ArrayFrom(arrayLike, mapfn, receiver) {
       AddArrayElement(this, result, k, mappedValue);
       k++;
     }
+    result.length = k;
+    return result;
   } else {
     var len = TO_LENGTH(items.length);
     result = %IsConstructor(this) ? new this(len) : new GlobalArray(len);