Chromium: Update and build fixes.

Changes included:
- Update versions.
- Use gyp package not gyp_svn1977.
- Remove icu from buildInputs, since this causes a build error due to inferference with use_system_icu=false.
- Remove the hack that inserts the absolute path into gyp files, and pass `--depth .` to gyp. This resolves the `third_party/angle` gyp error.
- Do a normal copy of the source code not a symlink copy. This resolves some link error where the symlinks interfere with relative paths (seems like because gyp resolves symlinks first). Note, this used to be worked around with the absolute path insertion hack.
- Change the bucketURL in update.nix to https (for more secure updates).