PDF Viewer: Prevent pdf:rotate-left icon from being flipped in RTL.

Fixed: 1168475
Change-Id: I3e63b2c710a12389e635803ccb473bf12e49e7dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2641985Reviewed-by: John Lee <johntlee@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Auto-Submit: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845733}

chrome/browser/resources/pdf/elements/viewer-pdf-toolbar-new.html

@@ -235,7 +235,7 @@
                                              fittingType_)]]"
         on-click="onFitToButtonClick_">
     </cr-icon-button>
-    <cr-icon-button iron-icon="pdf:rotate-left"
+    <cr-icon-button iron-icon="pdf:rotate-left" dir="ltr"
 <if expr="chromeos">
         disabled="[[annotationMode]]"
 </if>