Merge to M54: Temporarily work around crash when adding misspelling annotations to accessible strin…

content/browser/accessibility/browser_accessibility_cocoa.mm

Index: content/browser/accessibility/browser_accessibility_cocoa.mm
diff --git a/content/browser/accessibility/browser_accessibility_cocoa.mm b/content/browser/accessibility/browser_accessibility_cocoa.mm
index b6d73a815fff640a1df856ecb587d1396f53aafc..6c7d1564febc820c4d27fcb43f2e5e7cba06abf5 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -290,6 +290,13 @@ NSAttributedString* GetAttributedTextForTextMarkerRange(
     trim_length = static_cast<int>(end_object->GetText().length()) - end_offset;
   }
   int range_length = [text length] - start_offset - trim_length;
+
+  // http://crbug.com/651145
+  // This shouldn't happen, so this is a temporary workaround to prevent
+  // hard crashes.
+  if (range_length < 0)
+    return nil;
+
   DCHECK_GE(range_length, 0);
   NSRange range = NSMakeRange(start_offset, range_length);
   DCHECK_LE(NSMaxRange(range), [text length]);