Upgrading flow and fixing lint errors

Summary:
Upgrading to flow 0.91, fixing a bunch of `$FloxFixMe`s that were introduced by upgrading to 0.86.
Also fixing some linting issues.

Reviewed By: priteshrnandgaonkar

Differential Revision: D13900794

fbshipit-source-id: 5d0a1b62371f3b5d34b909bae0876583acb6f977

src/plugins/logs/LogWatcher.js

@@ -5,6 +5,8 @@
  * @format
  */
 
+import type {TableBodyRow} from 'flipper';
+
 import {
   PureComponent,
   FlexColumn,
@@ -129,11 +131,7 @@ export default class LogWatcher extends PureComponent<Props, State> {
     this.props.onChange(newCounters);
   };
 
-  buildRows = () => {
-    /* $FlowFixMe(>=0.86.0) This
-     * comment suppresses an error found when Flow v0.86 was
-     * deployed. To see the error, delete this comment and
-     * run Flow. */
+  buildRows = (): Array<TableBodyRow> => {
     return this.props.counters.map(({label, count, notify}, i) => ({
       columns: {
         expression: {