Disable DumpAccessibilityTreeTest.AccessibilityIframePostEnable test.

DumpAccessibilityTreeTest.AccessibilityIframePostEnable/win fails
on bulders:
https://ci.chromium.org/p/chromium/builders/ci/Win7%20Tests%20%281%29/92023
https://ci.chromium.org/p/chromium/builders/ci/win-asan/5481

TBR=kschmi@microsoft.com

Bug: None
Change-Id: I986c5083365d079388e8933231ad0c3745b4cbcc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1638201
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Reviewed-by: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665050}

content/browser/accessibility/dump_accessibility_tree_browsertest.cc

@@ -1305,11 +1305,19 @@ IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest, AccessibilityIframe) {
   RunHtmlTest(FILE_PATH_LITERAL("iframe.html"));
 }
 
+#if defined(OS_WIN)
+IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
+                       DISABLED_AccessibilityIframePostEnable) {
+  enable_accessibility_after_navigating_ = true;
+  RunHtmlTest(FILE_PATH_LITERAL("iframe.html"));
+}
+#else
 IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
                        AccessibilityIframePostEnable) {
   enable_accessibility_after_navigating_ = true;
   RunHtmlTest(FILE_PATH_LITERAL("iframe.html"));
 }
+#endif
 
 IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
                        AccessibilityIframeCrossProcess) {