Revert^3 "Enable loads and stores to global vars through property cell...

Revert^3 "Enable loads and stores to global vars through property cell shortcuts installed into par… (patchset #1 id:1 of https://codereview.chromium.org/1254723004/)

Reason for revert:
Suspected to cause Canary crashes

Original issue's description:
> Reland^2 "Enable loads and stores to global vars through property cell shortcuts installed into parent script context".
>
> This reverts commit 362b3785.
>
> R=ishell@chromium.org
>
> Committed: https://crrev.com/440ae014e56924b52337c3747221b79283f07b81
> Cr-Commit-Position: refs/heads/master@{#29849}

TBR=ishell@chromium.org,v8-mips-ports@googlegroups.com,plind44@gmail.com,bmeurer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true

Review URL: https://codereview.chromium.org/1260423002

Cr-Commit-Position: refs/heads/master@{#29905}

src/flag-definitions.h

@@ -677,7 +677,7 @@ DEFINE_BOOL(use_idle_notification, true,
 DEFINE_BOOL(use_ic, true, "use inline caching")
 DEFINE_BOOL(trace_ic, false, "trace inline cache state transitions")
 DEFINE_BOOL(vector_stores, false, "use vectors for store ics")
-DEFINE_BOOL(global_var_shortcuts, true, "use ic-less global loads and stores")
+DEFINE_BOOL(global_var_shortcuts, false, "use ic-less global loads and stores")
 
 // macro-assembler-ia32.cc
 DEFINE_BOOL(native_code_counters, false,