[es6] Implement for-of iterator finalization

test/mjsunit/mjsunit.status

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 # modification, are permitted provided that the following conditions are
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 #
 #     * Redistributions of source code must retain the above copyright
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@@ skipping 806 matching lines @@
   'harmony/private-symbols': [FAIL],
   'harmony/reflect-enumerate-delete': [FAIL],
   'harmony/reflect-enumerate-special-cases': [FAIL],
   'harmony/proxies-enumerate': [FAIL],
   'harmony/reflect-enumerate-opt': [FAIL],
   'harmony/reflect-enumerate': [FAIL],
   'harmony/destructuring': [FAIL],
   'harmony/regress/regress-4482': [FAIL],
   'harmony/reflect': [FAIL],
   'harmony/generators': [FAIL],
+  'harmony/iterator-close': [FAIL],
   'regress/regress-572589': [FAIL],
   'harmony/reflect-construct': [FAIL],
   'es6/promises': [FAIL],
   'deserialize-optimize-inner': [FAIL],
 
   # TODO(rmcilroy,4680): Check failed in
   # BytecodeGenerator::VisitFunctionLiteral - !shared_info.is_null().
   'regress/regress-crbug-429159': [FAIL],
 
   # TODO(rmcilroy,4680): Check failed: osr_normal_entry.
@@ skipping 139 matching lines @@
   # Tests taking too long.
   'array-functions-prototype-misc': [SKIP],
   'strong/implicit-conversions': [SKIP],
   'strong/load-element-mutate-backing-store': [SKIP],
 
   # Stack overflow.
   'big-array-literal': [SKIP],
 }],  # 'gcov_coverage'
 
 ]