Backport PR #6653

---------

**Commit 1:**
[internal] Replace empty var declaration with let

Any time there is a variable defined in a JS file without also storing a
value in it, we know that definition cannot be converted to a const, so
we convert it to a let.

For example:

`var blah;` becomes `let blah;`

Some of these things variables might be unused, and many others can
likely be switched to const with only minor refactoring, but the commit
is very large, so there are no changes in it other than the 1:1 switch.

* Original sha: bfc59e9
* Authored by Court Ewing <court@epixa.com> on 2016-03-24T22:27:29Z

backport.rej.md

@@ -0,0 +1,28 @@
+### Backport of PR [#6653](https://github.com/elastic/kibana/pull/6653) to branch 4.x failed
+
+
+**65** files could not be found in this branch,
+
+**177** patches failed to apply,
+while **30** patches were applied successfully.
+
+-------------------------------------
+
+The following script will rebase the commits that need to be backported onto
+this backport branch. Resolve any conflicts as you normally would in a rebase.
+You do *not* need to remove these backport.rej files, and you can add
+additional commits if that's necessary.
+
+```
+sh begin-backport.rej
+```
+
+Once the conficts are resolved on your local backport branch, the following
+script will remove the remnants of this backport commit and squash the newly
+resolved commits (and any others you may have added) into a single backport
+commit with the proper commit message. Finally, it'll replace the upstream
+backport branch (the one from the backport PR) with the result.
+
+```
+sh finish-backport.rej
+```

begin-backport.rej

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+#!/bin/sh
+
+REMOTE="upstream"
+BRANCH="jasper/backport/6653/4.x"
+STARTING_SHA="bfc59e9666d1cb593e6fe94b09322af5c6e3db07"
+ENDING_SHA="bfc59e9666d1cb593e6fe94b09322af5c6e3db07"
+
+WORKING_BRANCH="tmp/$BRANCH"
+
+git fetch $REMOTE
+
+git checkout -b $WORKING_BRANCH $ENDING_SHA
+git rebase $STARTING_SHA^ --onto $BRANCH

commit-message-backport.rej

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+Backport PR #6653
+---------
+
+**Commit 1:**
+[internal] Replace empty var declaration with let
+
+Any time there is a variable defined in a JS file without also storing a
+value in it, we know that definition cannot be converted to a const, so
+we convert it to a let.
+
+For example:
+
+`var blah;` becomes `let blah;`
+
+Some of these things variables might be unused, and many others can
+likely be switched to const with only minor refactoring, but the commit
+is very large, so there are no changes in it other than the 1:1 switch.
+
+* Original sha: bfc59e9666d1cb593e6fe94b09322af5c6e3db07
+* Authored by Court Ewing <court@epixa.com> on 2016-03-24T22:27:29Z

finish-backport.rej

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+#!/bin/sh
+
+REMOTE="upstream"
+BRANCH="jasper/backport/6653/4.x"
+
+COMMIT_MSG=`cat commit-message-backport.rej`
+
+WORKING_BRANCH="tmp/$BRANCH"
+
+git checkout $BRANCH
+git reset --hard $WORKING_BRANCH
+git branch -D $WORKING_BRANCH
+
+git reset --soft $REMOTE/$BRANCH
+git stash
+git reset --hard HEAD^
+git stash apply --index
+
+git commit -m "$COMMIT_MSG" --no-verify
+git push -f $REMOTE $BRANCH