Enable save form data in iframe

Bug: 881364
Change-Id: I6cef5aa5a8acc32bc797c3abbef0869a2f094e66
Reviewed-on: https://chromium-review.googlesource.com/c/1259782
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596349}

components/autofill/ios/browser/autofill_agent.mm

@@ -711,11 +711,6 @@ autofillManagerFromWebState:(web::WebState*)webState
                     hasUserGesture:(BOOL)hasUserGesture
                    formInMainFrame:(BOOL)formInMainFrame
                            inFrame:(web::WebFrame*)frame {
-  if (!formInMainFrame) {
-    // Saving from iframes is not implemented.
-    return;
-  }
-
   if (![self isAutofillEnabled])
     return;