deps: cherry-pick b767cde1e7 from upstream V8

Original commit message:

    [intl] unbreak build with ICU 57

    Remove a call to `icu::toUCharPtr()` that wasn't present in other
    similar looking call sites either, just reinterpret_cast directly.

    Fixes https://github.com/nodejs/node/issues/19656.

    Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
    Change-Id: If281ce0a39356aa8bd20efb24c3e4b52b06841a3
    Reviewed-on: https://chromium-review.googlesource.com/987953
    Reviewed-by: Daniel Ehrenberg <littledan@chromium.org>
    Commit-Queue: Ben Noordhuis <info@bnoordhuis.nl>
    Cr-Commit-Position: refs/heads/master@{#52311}

PR-URL: https://github.com/nodejs/node/pull/19710
Fixes: https://github.com/nodejs/node/issues/19656
Refs: b767cde1e7
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Steven R Loomis <srloomis@us.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

common.gypi

@@ -27,7 +27,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.5',
+    'v8_embedder_string': '-node.6',
 
     # Enable disassembler for `--print-code` v8 options
     'v8_enable_disassembler': 1,

deps/v8/src/runtime/runtime-intl.cc

@@ -626,8 +626,7 @@ RUNTIME_FUNCTION(Runtime_PluralRulesSelect) {
   icu::UnicodeString result = plural_rules->select(rounded);
   return *isolate->factory()
               ->NewStringFromTwoByte(Vector<const uint16_t>(
-                  reinterpret_cast<const uint16_t*>(
-                      icu::toUCharPtr(result.getBuffer())),
+                  reinterpret_cast<const uint16_t*>(result.getBuffer()),
                   result.length()))
               .ToHandleChecked();
 }