fix(browser): check for fetch on window (#313)

* changes without context

        autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

* docs: spelling correction for "targetting"

Co-authored-by: Benjamin E. Coe <[email protected]>

Source-Author: Samyak Jain <[email protected]>
Source-Date: Tue Nov 24 20:27:51 2020 +0530
Source-Repo: googleapis/synthtool
Source-Sha: 15013eff642a7e7e855aed5a29e6e83c39beba2a
Source-Link: googleapis/synthtool@15013ef

Author: yoshi-automation

packages/google-cloud-scheduler/README.md

@@ -117,7 +117,7 @@ Our client libraries follow the [Node.js release schedule](https://nodejs.org/en
 Libraries are compatible with all current _active_ and _maintenance_ versions of
 Node.js.
 
-Client libraries targetting some end-of-life versions of Node.js are available, and
+Client libraries targeting some end-of-life versions of Node.js are available, and
 can be installed via npm [dist-tags](https://docs.npmjs.com/cli/dist-tag).
 The dist-tags follow the naming convention `legacy-(version)`.