Sync for validator cpp engine and cpp htmlparser

[amaltas]

This is an automatically generated pull request.

[amp-owners-bot[bot]]

Hey @ampproject/wg-caching! These files were changed:

validator/cpp/engine/BUILD
validator/cpp/engine/validator-internal.cc
validator/cpp/engine/validator_test.cc
validator/cpp/htmlparser/BUILD
validator/cpp/htmlparser/allocator.h
validator/cpp/htmlparser/allocator_test.cc
validator/cpp/htmlparser/atomutil.cc
validator/cpp/htmlparser/bin/atomgen.cc
validator/cpp/htmlparser/bin/casetablegen.cc
validator/cpp/htmlparser/bin/entitytablegen.cc
validator/cpp/htmlparser/bin/validatorgen.cc
validator/cpp/htmlparser/casetable_test.cc
+34 more