Revert "Add V8_ENABLE_CHECKS define to public config"

This reverts commit 9c0471b3.

Reason for revert: blocks roll https://chromium-review.googlesource.com/c/chromium/src/+/656897

Original change's description:
> Add V8_ENABLE_CHECKS define to public config
> 
> We should add this define to external_config because it is used in
> public include v8.h (e.g.: https://cs.chromium.org/chromium/src/v8/include/v8.h?l=272&rcl=5cd6565d5ad06a8cb5a1d9d502d15a54e4fa5bbe)
> 
> Change-Id: I795a3de448029e34033cf8f83094bdea3590bbb9
> Reviewed-on: https://chromium-review.googlesource.com/654876
> Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
> Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47901}

TBR=gsathya@chromium.org,atimoxin@yandex-team.ru

Change-Id: I8265f78a9ab260b719226843afd649245e72434f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/657157Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47912}

BUILD.gn

@@ -205,9 +205,6 @@ config("external_config") {
   if (is_component_build) {
     defines = [ "USING_V8_SHARED" ]
   }
-  if (v8_enable_v8_checks) {
-    defines += [ "V8_ENABLE_CHECKS" ]  # Used in "include/v8.h".
-  }
   include_dirs = [
     "include",
     "$target_gen_dir/include",