Revert of [es6] Ship new ES6 instanceof operator semantics. (patchset #1 id:1...

Revert of [es6] Ship new ES6 instanceof operator semantics. (patchset #1 id:1 of https://codereview.chromium.org/1820903002/ )

Reason for revert:
Breaks two layout tests when rolling into Chromium. Tests needs investigation and most likely a rebaseline. The following are the tests that fail:

- imported/web-platform-tests/html/semantics/text-level-semantics/the-time-element/001.html
- fast/dom/Window/window-postmessage-clone-deep-array.html

https://storage.googleapis.com/chromium-layout-test-archives/V8-Blink_Linux_64/5594/layout-test-results/results.html

Original issue's description:
> [es6] Ship new ES6 instanceof operator semantics.
>
> R=hablich@chromium.org
> BUG=v8:4447
> LOG=n
>
> Committed: https://crrev.com/5836807ea89b96ecfb4bbd8febf0d67bb8dae9ed
> Cr-Commit-Position: refs/heads/master@{#34984}

TBR=hablich@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4447

Review URL: https://codereview.chromium.org/1823813003

Cr-Commit-Position: refs/heads/master@{#34995}

src/flag-definitions.h

@@ -210,6 +210,7 @@ DEFINE_IMPLICATION(es_staging, harmony_tailcalls)
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                                    \
   V(harmony_regexp_lookbehind, "harmony regexp lookbehind")                  \
+  V(harmony_instanceof, "harmony instanceof support")                        \
   V(harmony_object_values_entries, "harmony Object.values / Object.entries") \
   V(harmony_object_own_property_descriptors,                                 \
     "harmony Object.getOwnPropertyDescriptors()")                            \
@@ -219,7 +220,6 @@ DEFINE_IMPLICATION(es_staging, harmony_tailcalls)
 #define HARMONY_SHIPPING(V)                                           \
   V(harmony_array_prototype_values, "harmony Array.prototype.values") \
   V(harmony_function_name, "harmony Function name inference")         \
-  V(harmony_instanceof, "harmony instanceof support")                 \
   V(harmony_iterator_close, "harmony iterator finalization")          \
   V(harmony_regexps, "harmony regular expression extensions")         \
   V(harmony_unicode_regexps, "harmony unicode regexps")               \