Roll v8/ b6fd2f17b..a86e19715 (464 commits)

https://chromium.googlesource.com/v8/v8.git/+log/b6fd2f17bced..a86e1971579f

Version 12.3.219

Includes setting `build_with_v8_embedder` build override variable to
work with new method for embedders from https://crrev.com/c/5291895.

Created with:
  roll-dep v8

Fixed: pdfium:2124
Change-Id: If224ab8728f52463c04b703e3551092fd141a30a
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/116850
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Alan Screen <awscreen@chromium.org>
diff --git a/DEPS b/DEPS
index 27a9a78..b3735c2 100644
--- a/DEPS
+++ b/DEPS
@@ -199,7 +199,7 @@
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling v8
   # and whatever else without interference from each other.
-  'v8_revision': 'b6fd2f17bced4df7aeae5fb84c5e29b2d06c8f2f',
+  'v8_revision': 'a86e1971579f4165123467fa6ad378e552536b43',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling zlib
   # and whatever else without interference from each other.
diff --git a/build_overrides/build.gni b/build_overrides/build.gni
index b10e681..ca8910d 100644
--- a/build_overrides/build.gni
+++ b/build_overrides/build.gni
@@ -6,6 +6,11 @@
 # Chromium specific targets in a client project's GN file etc.
 build_with_chromium = false
 
+# Variable that can be used to support multiple build scenarios, like when
+# V8 is embedded within a target.
+# PDFium is one such embedder of V8.
+build_with_v8_embedder = true
+
 # PDFium builds don't support building java targets.
 enable_java_templates = false