Have XHR.getResponseHeader() return null in initial ready states.

LayoutTests/http/tests/xmlhttprequest/getResponseHeader-expected.txt

 CONSOLE ERROR: Refused to get unsafe header "SeT-COoKie"
 CONSOLE ERROR: Refused to get unsafe header "sEt-coOkIE2"
 CONSOLE ERROR: Refused to get unsafe header "SeT-COoKie"
 CONSOLE ERROR: Refused to get unsafe header "sEt-coOkIE2"
 CONSOLE ERROR: Refused to get unsafe header "SeT-COoKie"
 CONSOLE ERROR: Refused to get unsafe header "sEt-coOkIE2"
-Test page for bug 15356 and bug 29121
+Test the required behavior of XMLHttpRequest.getResponseHeader()
 
-Assertion: Invoking the getResponseHeader method when readyState >= 2 (HEADERS_RECEIVED) returns a header value if the header exists.
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
-Assertion: Invoking the getResponseHeader method with the parameter satisfying the following conditions causes getResponseHeader to return null:
 
-1a. The parameter case-insensitively matches Set-Cookie;
-1b. The parameter case-insensitively matches Set-Cookie2;
-2. The parameter does not match any header in the response;
-3a. The parameter is null (it is not a valid header name);
-3b. The parameter is "Content-Type:" (it is not a valid header name).
-PASSED 0 Content-Type: exception thrown.
-PASSED 1 Content-Type: exception thrown
-PASSED 2 Content-Type: ResponseHeader(Content-Type) returned a value.
-PASSED 2 SeT-COoKie: getResponseHeader(SeT-COoKie) returned null.
-PASSED 2 sEt-coOkIE2: getResponseHeader(sEt-coOkIE2) returned null.
-PASSED 2 xxx-mytest-headerabc: getResponseHeader(xxx-mytest-headerabc) returned null.
-PASSED 2 null: getResponseHeader(null) returned null.
-PASSED 2 Content-Type:: getResponseHeader(Content-Type:) returned null.
-PASSED 3 Content-Type: Content-Type
-PASSED 3 SeT-COoKie: getResponseHeader(SeT-COoKie) returned null.
-PASSED 3 sEt-coOkIE2: getResponseHeader(sEt-coOkIE2) returned null.
-PASSED 3 xxx-mytest-headerabc: getResponseHeader(xxx-mytest-headerabc) returned null.
-PASSED 3 null: getResponseHeader(null) returned null.
-PASSED 3 Content-Type:: getResponseHeader(Content-Type:) returned null.
-PASSED 4 Content-Type: Content-Type
-PASSED 4 SeT-COoKie: getResponseHeader(SeT-COoKie) returned null.
-PASSED 4 sEt-coOkIE2: getResponseHeader(sEt-coOkIE2) returned null.
-PASSED 4 xxx-mytest-headerabc: getResponseHeader(xxx-mytest-headerabc) returned null.
-PASSED 4 null: getResponseHeader(null) returned null.
-PASSED 4 Content-Type:: getResponseHeader(Content-Type:) returned null.
+PASS {state: 0}; headerValue = xhr.getResponseHeader('Content-Type'); did not throw exception.
+PASS headerValue is null
+PASS {state: 1}; headerValue = xhr.getResponseHeader('Content-Type'); did not throw exception.
+PASS headerValue is null
+PASS Header 'Content-Type' is null in ready state 1.
+PASS xhr.open("GET", "resources/1251.html", true); did not throw exception.
+PASS {state: 1}; headerValue = xhr.getResponseHeader('Content-Type'); did not throw exception.
+PASS headerValue is null
+PASS xhr.send(null); did not throw exception.
+PASS {state: 2}; headerValue = xhr.getResponseHeader('Content-Type'); did not throw exception.
+PASS headerValue is non-null.
+PASS {state: 2}; headerValue = xhr.getResponseHeader('SeT-COoKie'); did not throw exception.
+PASS headerValue is null
+PASS {state: 2}; headerValue = xhr.getResponseHeader('sEt-coOkIE2'); did not throw exception.
+PASS headerValue is null
+PASS {state: 2}; headerValue = xhr.getResponseHeader('xxx-mytest-headerabc'); did not throw exception.
+PASS headerValue is null
+PASS {state: 2}; headerValue = xhr.getResponseHeader('null'); did not throw exception.
+PASS headerValue is null
+PASS {state: 2}; headerValue = xhr.getResponseHeader('Content-Type:'); did not throw exception.
+PASS headerValue is null
+PASS {state: 3}; headerValue = xhr.getResponseHeader('Content-Type'); did not throw exception.
+PASS headerValue is non-null.
+PASS result is savedHeader
+PASS {state: 3}; headerValue = xhr.getResponseHeader('SeT-COoKie'); did not throw exception.
+PASS headerValue is null
+PASS {state: 3}; headerValue = xhr.getResponseHeader('sEt-coOkIE2'); did not throw exception.
+PASS headerValue is null
+PASS {state: 3}; headerValue = xhr.getResponseHeader('xxx-mytest-headerabc'); did not throw exception.
+PASS headerValue is null
+PASS {state: 3}; headerValue = xhr.getResponseHeader('null'); did not throw exception.
+PASS headerValue is null
+PASS {state: 3}; headerValue = xhr.getResponseHeader('Content-Type:'); did not throw exception.
+PASS headerValue is null
+PASS {state: 4}; headerValue = xhr.getResponseHeader('Content-Type'); did not throw exception.
+PASS headerValue is non-null.
+PASS result is savedHeader
+PASS {state: 4}; headerValue = xhr.getResponseHeader('SeT-COoKie'); did not throw exception.
+PASS headerValue is null
+PASS {state: 4}; headerValue = xhr.getResponseHeader('sEt-coOkIE2'); did not throw exception.
+PASS headerValue is null
+PASS {state: 4}; headerValue = xhr.getResponseHeader('xxx-mytest-headerabc'); did not throw exception.
+PASS headerValue is null
+PASS {state: 4}; headerValue = xhr.getResponseHeader('null'); did not throw exception.
+PASS headerValue is null
+PASS {state: 4}; headerValue = xhr.getResponseHeader('Content-Type:'); did not throw exception.
+PASS headerValue is null
+PASS successfullyParsed is true
 
+TEST COMPLETE
+