This embeds code for off-heap-safe builtins into the binary. Actual
execution of embedded code is not implemented yet.

The embedded file has the following format:

namespace v8 {
namespace internal {

namespace {

V8_EMBEDDED_TEXT_HEADER(v8_embedded_blob_)
__asm__( /* builtin offsets and lengths */ );
__asm__(V8_ASM_LABEL("Builtins_RecordWrite"));
__asm__( /* binary instruction stream */ );
/* Repeat for other builtins. */

extern "C" const uint8_t v8_embedded_blob_[];
static const uint32_t v8_embedded_blob_size_ = /* size in bytes */;

}  // namespace

const uint8_t* DefaultEmbeddedBlob() { return v8_embedded_blob_; }
uint32_t DefaultEmbeddedBlobSize() { return v8_embedded_blob_size_; }

}  // namespace internal
}  // namespace v8

Bug: v8:6666
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng;luci.v8.try:v8_linux64_fyi_rel_ng
Change-Id: Ic989f01da69ebe2863f31d934bfbe2c5d6e80864
Reviewed-on: https://chromium-review.googlesource.com/946011
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51759}