Removed DT inject() script since it's no longer being used

packages/react-devtools-extensions/src/inject.js

@@ -1,24 +0,0 @@
-/* global chrome */
-
-export default function inject(scriptName: string, done: ?Function) {
-  const source = `
-  // the prototype stuff is in case document.createElement has been modified
-  (function () {
-    var script = document.constructor.prototype.createElement.call(document, 'script');
-    script.src = "${scriptName}";
-    script.charset = "utf-8";
-    document.documentElement.appendChild(script);
-    script.parentNode.removeChild(script);
-  })()
-  `;
-
-  chrome.devtools.inspectedWindow.eval(source, function(response, error) {
-    if (error) {
-      console.log(error);
-    }
-
-    if (typeof done === 'function') {
-      done();
-    }
-  });
-}