Revert "[regexp] Include unicode/uvernum.h in parser"

This reverts commit 0db90bc.

Reason for revert: https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20noi18n%20-%20debug/builds/17335

You need to also check whether i18n is on, e.g. #ifdef V8_INTL_SUPPORT.

Original change's description:
> [regexp] Include unicode/uvernum.h in parser
> 
> This patch explicitly includes unicode/uvernum.h in the regular
> expression parser.
> 
> It should be removed once we no longer need to check
> `U_ICU_VERSION_MAJOR_NUM` during preprocessing, i.e. once Node.js
> updates their ICU. This is an ongoing effort:
> nodejs/node#16876
> 
> BUG=v8:4743
> 
> Change-Id: I3cd9447b481249a9035d9fb00745057da8809c58
> Reviewed-on: https://chromium-review.googlesource.com/758407
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Commit-Queue: Mathias Bynens <mathias@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49253}

TBR=yangguo@chromium.org,jshin@chromium.org,jgruber@chromium.org,mathias@chromium.org

Change-Id: I58d6b7a49b707c97153b8b0aec141248f5c669e1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:4743
Reviewed-on: https://chromium-review.googlesource.com/759777
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49255}

src/regexp/regexp-parser.cc

@@ -14,10 +14,6 @@
 #include "src/regexp/jsregexp.h"
 #include "src/utils.h"
 
-// TODO(mathias): Remove this when we no longer need to check
-// `U_ICU_VERSION_MAJOR_NUM`.
-#include "unicode/uvernum.h"
-
 #ifdef V8_INTL_SUPPORT
 #include "unicode/uniset.h"
 #endif  // V8_INTL_SUPPORT