Add LayoutTests for mixed range response handling.

LayoutTests/http/tests/serviceworker/chromium/resources/service-worker-generated-mixed-response-worker.js

+self.addEventListener('fetch', function(event) {
+    if (event.request.url.indexOf('blank.html') != -1) {
+      // The request is for the page load.
+      return;
+    }
+    if (event.request.headers.get('range') != 'bytes=0-') {
+      // The request is not the first range request.
+      return;
+    }
+    event.respondWith(
+        new Response(
+            'Ogg',
+            {
+              status: 206,
+              headers: {
+                'content-type': 'audio/ogg',
+                'content-range': 'bytes 0-3/12983'
+              }
+            }));
+});

[falken, 2015/07/03 04:10:36]

indent two spaces

[horo, 2015/07/06 11:45:40]

Done.