[XMLHttpRequest] Stop throwing for network error in async mode

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

Index: LayoutTests/http/tests/xmlhttprequest/cross-origin-unsupported-url-expected.txt
diff --git a/LayoutTests/http/tests/xmlhttprequest/cross-origin-unsupported-url-expected.txt b/LayoutTests/http/tests/xmlhttprequest/cross-origin-unsupported-url-expected.txt
index 8e7b6d5114a015eb7ec1e2152b220f420f44a8aa..deef009f3feb5cf026661907f52c74bdc0e66d3b 100644
--- a/LayoutTests/http/tests/xmlhttprequest/cross-origin-unsupported-url-expected.txt
+++ b/LayoutTests/http/tests/xmlhttprequest/cross-origin-unsupported-url-expected.txt
@@ -12,21 +12,21 @@ On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE
 
 
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'http://localhost:1291a/'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'http://localhost:1291a/'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'ftp://127.0.0.1/'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'ftp://127.0.0.1/'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'localhost:8080/'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'localhost:8080/'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'tel:1234'..
+PASS xhr.send() did not throw exception.
 PASS errorEvent.type is "error"
-PASS xhr.send() threw exception NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'tel:1234'..
+PASS xhr.send() did not throw exception.
 PASS successfullyParsed is true
 
 TEST COMPLETE