Convert gr-diff-host to typescript

The change converts the following files to typescript:

* elements/diff/gr-diff-host/gr-diff-host.ts

Change-Id: Ie565ab753fea6909790729b8e42410d39c437612
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-processor/gr-diff-processor.ts b/polygerrit-ui/app/elements/diff/gr-diff-processor/gr-diff-processor.ts
index a85af34..39e12ca 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-processor/gr-diff-processor.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-processor/gr-diff-processor.ts
@@ -31,7 +31,7 @@
 import {CancelablePromise, util} from '../../../scripts/util';
 import {customElement, property} from '@polymer/decorators';
 import {DiffContent} from '../../../types/common';
-import {DiffSide} from '../gr-diff/gr-diff-utils';
+import {Side} from '../../../constants/constants';
 
 const WHOLE_FILE = -1;
 
@@ -567,8 +567,8 @@
     for (let i = 0; i < numLines; i++) {
       // If this line should not be collapsed.
       if (
-        this.keyLocations[DiffSide.LEFT][leftOffset + i] ||
-        this.keyLocations[DiffSide.RIGHT][rightOffset + i]
+        this.keyLocations[Side.LEFT][leftOffset + i] ||
+        this.keyLocations[Side.RIGHT][rightOffset + i]
       ) {
         // If any lines have been accumulated into the chunk leading up to
         // this non-collapse line, then add them as a chunk and start a new