Fix roll_webgl_conformance.py

Remove import from upload module. Upload doesn't seem to be actually used. Simply removing it will make
the script work again.

Bug: 1018475
Change-Id: Ib30850f1c7b4a0ad2cb1596b1051662651514be2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1885096
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710143}

tools/roll_webgl_conformance.py

@@ -53,10 +53,6 @@ sys.path.insert(0, os.path.join(SRC_DIR, 'build'))
 import find_depot_tools
 find_depot_tools.add_depot_tools_to_path()
 import roll_dep_svn
-from third_party import upload
-
-# Avoid depot_tools/third_party/upload.py print verbose messages.
-upload.verbosity = 0  # Errors only.
 
 CHROMIUM_GIT_URL = 'https://chromium.googlesource.com/chromium/src.git'
 CL_ISSUE_RE = re.compile('^Issue number: ([0-9]+) \((.*)\)$')