Early continue. NFC.

The original code is a big `if` and `else` which ends with `continue`
like this:

  if (cond) {
    ...
    // fall through
  } else {
    ...
    continue;
  }

This patch rewrites it with the following.

  if (!cond) {
    ...
    continue;
  }
  ...

llvm-svn: 298672