This CL modifies java_cpp_enum.py to preserve comments on the
enums in the generated Java file.
The comments are useful for developers who usually read the
JavaDoc and not the C++ files.
BUG=634092
Review-Url: https://codereview.chromium.org/2210633002
Cr-Original-Commit-Position: refs/heads/master@{#410047}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: ea986397d77dc45b5b272ad68d00cc6063ee6987