Added NavigationContext::IsPost.

ios/web/web_state/navigation_context_impl.mm

Index: ios/web/web_state/navigation_context_impl.mm
diff --git a/ios/web/web_state/navigation_context_impl.mm b/ios/web/web_state/navigation_context_impl.mm
index 80a09c43f9c90e93078d69d2f470e182caea72b2..62cf17e5d310b57d7980547d1f2cce9408fe24e0 100644
--- a/ios/web/web_state/navigation_context_impl.mm
+++ b/ios/web/web_state/navigation_context_impl.mm
@@ -48,6 +48,10 @@ bool NavigationContextImpl::IsSameDocument() const {
   return is_same_document_;
 }
 
+bool NavigationContextImpl::IsPost() const {
+  return is_post_;
+}
+
 NSError* NavigationContextImpl::GetError() const {
   return error_;
 }
@@ -60,6 +64,10 @@ void NavigationContextImpl::SetIsSameDocument(bool is_same_document) {
   is_same_document_ = is_same_document;
 }
 
+void NavigationContextImpl::SetIsPost(bool is_post) {
+  is_post_ = is_post;
+}
+
 void NavigationContextImpl::SetError(NSError* error) {
   error_.reset(error);
 }