fix($http): properly access request headers with mixed case

Fixes #10881

Author: pkozlowski-opensource

src/ng/http.js

@@ -56,9 +56,9 @@ function parseHeaders(headers) {
 
 
 /**
- * Returns a function that provides access to parsed headers.
+ * Returns a function that provides access to headers.
  *
- * Headers are lazy parsed when first requested.
+ * Headers provided as string are lazy parsed when first requested.
  * @see parseHeaders
  *
  * @param {(string|Object)} headers Headers to provide access to.
@@ -71,14 +71,16 @@ function headersGetter(headers) {
   var headersObj = isObject(headers) ? headers : undefined;
 
   return function(name) {
+    var existingHeaderName, lowercaseName = lowercase(name);
     if (!headersObj) headersObj =  parseHeaders(headers);
 
     if (name) {
-      var value = headersObj[lowercase(name)];
-      if (value === void 0) {
-        value = null;
+      for (existingHeaderName in headersObj) {
+        if (lowercase(existingHeaderName) === lowercaseName) {
+          return isDefined(headersObj[existingHeaderName]) ? headersObj[existingHeaderName] : null;
+        }
       }
-      return value;
+      return null;
     }
 
     return headersObj;

test/ng/httpSpec.js

@@ -1038,6 +1038,18 @@ describe('$http', function() {
           expect(callback).toHaveBeenCalledOnce();
         });
 
+        it('should have access to request headers with mixed case', function() {
+          $httpBackend.expect('POST', '/url', 'header1').respond(200);
+          $http.post('/url', 'req', {
+            headers: {H1: 'header1'},
+            transformRequest: function(data, headers) {
+              return headers('H1');
+            }
+          }).success(callback);
+          $httpBackend.flush();
+
+          expect(callback).toHaveBeenCalledOnce();
+        });
 
         it('should pipeline more functions', function() {
           function first(d, h) {return d + '-first' + ':' + h('h1');}