Revert "Revive WorkerThreadableLoader for sync XHR again"

This reverts commit b1e172c8.

Bug: 706331
Change-Id: I6d9ab8095e18feb76ddb1f395bbf665186b97617
Reviewed-on: https://chromium-review.googlesource.com/1077372Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562755}

third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/workers/access-control-basic-get-fail-non-simple-expected.txt

-CONSOLE ERROR: Failed to load http://localhost:8000/xmlhttprequest/resources/access-control-basic-get-fail-non-simple.cgi: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://127.0.0.1:8000' is therefore not allowed access.
+CONSOLE ERROR: line 37: Failed to load http://localhost:8000/xmlhttprequest/resources/access-control-basic-get-fail-non-simple.cgi: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://127.0.0.1:8000' is therefore not allowed access.
 GET should not trigger a preflight request from a worker unless it has non-simple headers.
 
 PASS: Cross-domain access allowed for simple get.

third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/workers/cross-origin-unsupported-url-expected.txt

-CONSOLE ERROR: Failed to load ftp://127.0.0.1/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
+CONSOLE ERROR: line 20: Failed to load ftp://127.0.0.1/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 CONSOLE ERROR: line 1: Failed to load ftp://127.0.0.1/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
-CONSOLE ERROR: Failed to load ftp://127.0.0.1/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
+CONSOLE ERROR: line 20: Failed to load ftp://127.0.0.1/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 CONSOLE ERROR: line 1: Failed to load ftp://127.0.0.1/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
-CONSOLE ERROR: Failed to load localhost:8080/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
+CONSOLE ERROR: line 20: Failed to load localhost:8080/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 CONSOLE ERROR: line 1: Failed to load localhost:8080/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
-CONSOLE ERROR: Failed to load localhost:8080/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
+CONSOLE ERROR: line 20: Failed to load localhost:8080/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 CONSOLE ERROR: line 1: Failed to load localhost:8080/: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
-CONSOLE ERROR: Failed to load tel:1234: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
+CONSOLE ERROR: line 20: Failed to load tel:1234: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 CONSOLE ERROR: line 1: Failed to load tel:1234: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
-CONSOLE ERROR: Failed to load tel:1234: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
+CONSOLE ERROR: line 20: Failed to load tel:1234: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 CONSOLE ERROR: line 1: Failed to load tel:1234: Cross origin requests are only supported for protocol schemes: http, data, chrome, https.
 [Worker] Test cross-origin XHRs to CORS-unsupported protocol schemes in the URL.
 

third_party/blink/renderer/core/loader/threadable_loader.cc

@@ -33,7 +33,6 @@
 #include "third_party/blink/renderer/core/execution_context/execution_context.h"
 #include "third_party/blink/renderer/core/loader/document_threadable_loader.h"
 #include "third_party/blink/renderer/core/loader/threadable_loading_context.h"
-#include "third_party/blink/renderer/core/loader/worker_threadable_loader.h"
 #include "third_party/blink/renderer/core/workers/worker_global_scope.h"
 
 namespace blink {
@@ -57,12 +56,6 @@ void ThreadableLoader::LoadResourceSynchronously(
     ThreadableLoaderClient& client,
     const ThreadableLoaderOptions& options,
     const ResourceLoaderOptions& resource_loader_options) {
-  if (context.IsWorkerGlobalScope()) {
-    WorkerThreadableLoader::LoadResourceSynchronously(
-        ToWorkerGlobalScope(context), request, client, options,
-        resource_loader_options);
-    return;
-  }
   DocumentThreadableLoader::LoadResourceSynchronously(
       *ThreadableLoadingContext::Create(context), request, client, options,
       resource_loader_options);