[iOS] Make JS injection validation code robust to unexpected types

The result object returned by |WKWebView evaluateJavaScript
completionHandler:| may have an unexpected type. The check to determine
if the windowID has been injected should not crash if the result object
has an unexpected type.

Fixed: 1050940
Change-Id: I326d474e461286ed02b90191ab2868d15afe957d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2073059
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Auto-Submit: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744547}

ios/web/js_messaging/crw_js_window_id_manager.mm

@@ -65,8 +65,15 @@ - (void)inject {
                  return;
                }
 
-               DCHECK_EQ(CFBooleanGetTypeID(),
-                         CFGetTypeID((__bridge CFTypeRef)result));
+               // If |result| is an incorrect type, do not check its value.
+               // Also do not attempt to re-inject scripts as it may lead to
+               // endless recursion attempting to inject the scripts correctly.
+               if (result && CFBooleanGetTypeID() !=
+                                 CFGetTypeID((__bridge CFTypeRef)result)) {
+                 NOTREACHED();
+                 return;
+               }
+
                if (![result boolValue]) {
                  // WKUserScript has not been injected yet. Retry window id
                  // injection, because it is critical for the system to