Revert "Add tests to exercise hypertext on hidden iframes"

This reverts commit d49dcd89.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 836899 as the
culprit for flakes in the build cycles as shown on:
https://analysis.chromium.org/p/chromium/flake-portal/analysis/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vZDQ5ZGNkODk1ZGNkMjgwZjBlYWZlNTRkZTdiNWJkZGJkY2ZiZDFhNQw

Sample Failed Build: https://ci.chromium.org/b/8860879057915778784

Sample Failed Step: content_browsertests

Sample Flaky Test: All/DumpAccessibilityTreeTest.AccessibilityIframeAriaHidden/linux

Original change's description:
> Add tests to exercise hypertext on hidden iframes
> 
> TBR=kbabbitt@microsoft.com
> 
> Bug: None
> Change-Id: I14d580e7e20409fdf2ecc4d8a9294076f11ec07d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2584562
> Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
> Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#836899}


Change-Id: I79641c036c742b0d893e91dc2fb5f69d4e0278cf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: None
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2592395
Cr-Commit-Position: refs/heads/master@{#836973}

content/browser/accessibility/dump_accessibility_tree_browsertest.cc

@@ -1692,11 +1692,6 @@ IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest, AccessibilityIframe) {
   RunHtmlTest(FILE_PATH_LITERAL("iframe.html"));
 }
 
-IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
-                       AccessibilityIframeAriaHidden) {
-  RunHtmlTest(FILE_PATH_LITERAL("iframe-aria-hidden.html"));
-}
-
 IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
                        AccessibilityIframeScrollable) {
   RunHtmlTest(FILE_PATH_LITERAL("iframe-scrollable.html"));

content/test/data/accessibility/html/iframe-aria-hidden-expected-android.txt

-android.webkit.WebView focusable focused scrollable
-++android.view.View invisible
-++android.view.View invisible
\ No newline at end of file

content/test/data/accessibility/html/iframe-aria-hidden-expected-auralinux.txt

-[document web]
-++[internal frame]
-++[internal frame]

content/test/data/accessibility/html/iframe-aria-hidden-expected-blink.txt

-rootWebArea
-++genericContainer ignored
-++++genericContainer ignored
-++++++iframe invisible
-++++++iframe invisible

content/test/data/accessibility/html/iframe-aria-hidden-expected-mac.txt

-AXWebArea
\ No newline at end of file

content/test/data/accessibility/html/iframe-aria-hidden-expected-uia-win.txt

-Document
-++Document IsControlElement=false
-++Document IsControlElement=false
\ No newline at end of file

content/test/data/accessibility/html/iframe-aria-hidden-expected-win.txt

-ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE ia2_hypertext='<obj0><obj1>'
-++IA2_ROLE_INTERNAL_FRAME INVISIBLE
-++IA2_ROLE_INTERNAL_FRAME INVISIBLE
\ No newline at end of file

content/test/data/accessibility/html/iframe-aria-hidden.html

-<!--
-@WIN-ALLOW:ia2_hypertext=*
--->
-<iframe tabindex="-1" aria-hidden="true" style="position: absolute; width: 9em; height: 9em; top: -99em;"></iframe>
-<iframe aria-hidden="true" style="position: absolute; width: 9em; height: 9em; top: -99em;"></iframe>

content/test/data/accessibility/html/iframe.html

@@ -3,7 +3,6 @@
 @WIN-ALLOW:ia2_hypertext=*
 @WIN-ALLOW:parent=*
 @WIN-ALLOW:window_class=*
-@WIN-ALLOW:ia2_hypertext=*
 @BLINK-ALLOW:scrollable=*
 TODO(accessibility) this should eventually show scrollable=false for both the main doc and iframe. See matching TODO in AXObject::IsUserScrollable().
 -->