Convert print statements to Python 3 style

Ran "2to3 -w -n -f print ./" and manually added imports.
Ran "^\s*print " and "\s+print " to find batch/shell scripts, comments and the like with embedded code, and updated them manually.
Also manually added imports to files, which used print as a function, but were missing the import.

The scripts still work with Python 2.
There are no intended behaviour changes.

Bug: 942522
Change-Id: Id777e4d4df4adcdfdab1b18bde89f235ef491b9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1595684
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Auto-Submit: Raul Tambre <raul@tambre.ee>
diff --git a/dart_format.py b/dart_format.py
index ae85602..5fec2a3 100755
--- a/dart_format.py
+++ b/dart_format.py
@@ -10,6 +10,8 @@
 This tool is named dart_format.py instead of dartfmt to parallel
 clang_format.py, which is in this same repository."""
 
+from __future__ import print_function
+
 import os
 import subprocess
 import sys
@@ -42,14 +44,14 @@
   try:
     tool = FindDartFmtToolInChromiumTree()
   except NotFoundError, e:
-    print >> sys.stderr, e
+    print(e, file=sys.stderr)
     sys.exit(1)
 
   # Add some visibility to --help showing where the tool lives, since this
   # redirection can be a little opaque.
   help_syntax = ('-h', '--help', '-help', '-help-list', '--help-list')
   if any(match in args for match in help_syntax):
-    print '\nDepot tools redirects you to the dartfmt at:\n    %s\n' % tool
+    print('\nDepot tools redirects you to the dartfmt at:\n    %s\n' % tool)
 
   return subprocess.call([tool] + sys.argv[1:])