Fix releases script after git migration.

tools/push-to-trunk/releases.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script retrieves the history of all V8 branches and trunk revisions and
 # their corresponding Chromium revisions.
 
 # Requires a chromium checkout with branch heads:
 # gclient sync --with_branch_heads
@@ skipping 304 matching lines @@
     cwd = self._options.chromium
     self.GitCheckout("master", cwd=cwd)
     self.GitPull(cwd=cwd)
     self.GitCreateBranch(self.Config("BRANCHNAME"), cwd=cwd)
 
 
 def ConvertToCommitNumber(step, revision):
   # Simple check for git hashes.
   if revision.isdigit() and len(revision) < 8:
     return revision
-  return step.GitConvertToSVNRevision(
+  return step.GetCommitPositionNumber(
       revision, cwd=os.path.join(step._options.chromium, "v8"))
 
 
 class RetrieveChromiumV8Releases(Step):
   MESSAGE = "Retrieve V8 releases from Chromium DEPS."
 
   def RunStep(self):
     cwd = self._options.chromium
     releases = filter(
         lambda r: r["branch"] in [self.vc.CandidateBranch(),
@@ skipping 161 matching lines @@
       UpdateChromiumCheckout,
       RetrieveChromiumV8Releases,
       RietrieveChromiumBranches,
       CleanUp,
       WriteOutput,
     ]
 
 
 if __name__ == "__main__":  # pragma: no cover
   sys.exit(Releases().Run())