Reland "Fix form resubmissions happening silently."

Source/core/loader/DocumentLoader.cpp

Index: Source/core/loader/DocumentLoader.cpp
diff --git a/Source/core/loader/DocumentLoader.cpp b/Source/core/loader/DocumentLoader.cpp
index 4c92b95ab0f40677d34317a69679bb57f30984aa..e6eccb932a14fb15770c475d6a4af9426c79de81 100644
--- a/Source/core/loader/DocumentLoader.cpp
+++ b/Source/core/loader/DocumentLoader.cpp
@@ -346,11 +346,8 @@ void DocumentLoader::finishedLoading(double finishTime)
     clearMainResourceHandle();
 }
 
-bool DocumentLoader::isPostOrRedirectAfterPost(const ResourceRequest& newRequest, const ResourceResponse& redirectResponse)
+bool DocumentLoader::isRedirectAfterPost(const ResourceRequest& newRequest, const ResourceResponse& redirectResponse)
 {
-    if (newRequest.httpMethod() == "POST")
-        return true;
-
     int status = redirectResponse.httpStatusCode();
     if (((status >= 301 && status <= 303) || status == 307)
         && m_originalRequest.httpMethod() == "POST")
@@ -452,8 +449,7 @@ void DocumentLoader::willSendRequest(ResourceRequest& newRequest, const Resource
     // If we're fielding a redirect in response to a POST, force a load from origin, since
     // this is a common site technique to return to a page viewing some data that the POST
     // just modified.
-    // Also, POST requests always load from origin, but this does not affect subresources.
-    if (newRequest.cachePolicy() == UseProtocolCachePolicy && isPostOrRedirectAfterPost(newRequest, redirectResponse))
+    if (newRequest.cachePolicy() == UseProtocolCachePolicy && isRedirectAfterPost(newRequest, redirectResponse))
         newRequest.setCachePolicy(ReloadIgnoringCacheData);
 
     Frame* parent = m_frame->tree()->parent();