build: move libcc patches to electron repo (#14104)

In the GN build, libchromiumcontent is no longer a distinct library, but
merely a container for a set of scripts and patches. Maintaining those
patches in a separate repository is tedious and error-prone, so merge
them into the main repo.

Once this is merged and GN is the default way to build Electron, the
libchromiumcontent repository can be archived.

patches/common/v8/backport_b767cde1e7.patch

@@ -0,0 +1,15 @@
+b767cde1e7bb94b3fea13f2d7e10cd90e6813d6c
+diff --git a/src/runtime/runtime-intl.cc b/src/runtime/runtime-intl.cc
+index c359a1e5a1..198610a652 100644
+--- a/src/runtime/runtime-intl.cc
++++ b/src/runtime/runtime-intl.cc
+@@ -620,8 +620,7 @@ 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();
+ }