chore(lint): remove unused imports (#11923)

This was done automatically by tslint, which can now fix issues it finds.
The fixer is still pending in PR https://github.com/palantir/tslint/pull/1568
Also I have a local bugfix for https://github.com/palantir/tslint/issues/1569
which causes too many imports to be deleted.

modules/benchmarks/src/tree/incremental_dom/index.ts

@@ -1,5 +1,5 @@
 import {bindAction, profile} from '../../util';
-import {TreeNode, buildTree, emptyTree} from '../util';
+import {buildTree, emptyTree} from '../util';
 import {TreeComponent} from './tree';
 const {patch} = require('incremental-dom');