Move the key positions calculation up from gr-diff-builder to gr-diff

This change removes the comment model dependency in gr-diff-builder,
allowing an easier reuse of the component.

A follow up change will remove the comment model dependency in gr-diff
by replacing it with threadEl model.

Change-Id: I2b8c3394a5aaa5b8880af24a057008eb2692b245
diff --git a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
index 862db10..e587953 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
@@ -293,8 +293,7 @@
               line-wrapping="[[lineWrapping]]"
               is-image-diff="[[isImageDiff]]"
               base-image="[[baseImage]]"
-              revision-image="[[revisionImage]]"
-              line-of-interest="[[lineOfInterest]]">
+              revision-image="[[revisionImage]]">
             <slot></slot>
             <table
                 id="diffTable"