Revert "[ios] extract JS injection from web controller"

This reverts commit 950edae370f90408bef24e5084ff0739788708a4.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> [ios] extract JS injection from web controller
> 
> Moved JS injection relative code to a new class in crw_js_injector.
> Updated CRWJSInjectionEvaluator to have a executeUserJavaScript that
> seemed to logicaly have been there already.
> 
> Bug: 954137
> Change-Id: I3a80c995de82329f22532d791c20d84b9ecbfe46
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1571703
> Commit-Queue: David Jean <djean@chromium.org>
> Reviewed-by: Eugene But <eugenebut@chromium.org>
> Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
> Reviewed-by: Mark Cogan <marq@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#657195}

TBR=marq@chromium.org,eugenebut@chromium.org,michaeldo@chromium.org,gambard@chromium.org,mrsuyi@chromium.org,djean@chromium.org

Change-Id: I279e26687f4ddd6ed1c1afc4e3b56c9e572f1be8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 954137
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1598823
Reviewed-by: David Jean <djean@chromium.org>
Commit-Queue: David Jean <djean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657227}
12 files changed