Disable one-shot optimizations by default

There was preformance regression with one-shot optimizations (
https://bugs.chromium.org/p/chromium/issues/detail?id=876839#c4).
Disable the one shot optimizations by default until the regrssion is fixed.

Change-Id: I031ac2e0151e06fb2116f417ad3d9a3d04da16ac
Reviewed-on: https://chromium-review.googlesource.com/1189823Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Chandan Reddy <chandanreddy@google.com>
Cr-Commit-Position: refs/heads/master@{#55455}

src/flag-definitions.h

@@ -317,7 +317,7 @@ DEFINE_BOOL(optimize_for_size, false,
             "speed")
 
 // Flag for one shot optimiztions.
-DEFINE_BOOL(enable_one_shot_optimization, true,
+DEFINE_BOOL(enable_one_shot_optimization, false,
             "Enable size optimizations for the code that will "
             "only be executed once")