message: tfdbg: Fix a bug in source file content reading
  Previously, calling strip() removed not only the trailing newline character, but also any leading spaces and tabs, which actually should be preserved. This CL fixes it.
diff: @@ -39,9 +39,7 @@ def _load_debugged_source_file(file_path, source_file_proto):
  source_file_proto.bytes = file_stat.length
  try:
  with gfile.Open(file_path, "r") as f:
  - source_lines = f.readlines()
  - for line in source_lines:
  - source_file_proto.lines.append(line.strip())
  + source_file_proto.lines.extend(f.read().splitlines())
  except IOError:
  pass
  