import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1163826 - Add remainder of top .jp sites to CSS unprefixing service whitelist. r=dholbert (8ed22f2638)
- Bug 1165834: Add alicdn.com (used by taobao.com) to the CSS Unprefixing Service whitelist. r=miketaylr (30d150c28c)
- Bug 1166792 - Add 3rd batch of top .jp sites to CSS unprefixing service whitelists. r=dholbert (e4073c1f09)
- Bug 1170375 - Add 4th batch of top .jp sites to CSS unprefixing service whitelists. r=dholbert (d741e57cb0)
- Bug 1207850 - Temporary fix for canceling the pump used by FetchBody. r=nsm (bc85cb1500)
- Bug 1224865: Don't set a document in FetchDriver for requests in workers. r=bkelly (7bcb0bd16b)
- Bug 1108181 - Make Headers iterable; r=bzbarsky (da8d6f8bb2)
- Bug 1217501 P5 Relax guard checking on Headers with existing headers. r=ehsan (75ec3b6ae5)
- Bug 1207882 - Use a separate build target for config/buildid. r=gps (ad9f536aac)
- Bug 1216697 - Unship Request.cache until the implementation is finished; r=bzbarsky (49264a21d8)
- Bug 1218119 - Simplify defining worker prefs; r=baku (8987aa23c3)
- namespace (d88c3b7fc6)
- Bug 1179489 - Don't count service workers towards an origin's max worker quota; r=nsm (ce5e1345ba)
- Bug 1151646 - Cleanup, r=khuey. (d119d19ea7)
- Bug 1118778 - Write upload properties from upload.py; r=glandium (f8745ffda8)
- Bug 1194741 - Display upload output; r=nalexander (7adaa41d11)
- Bug 1197293 - allow for TC builds that don't use 'make upload'; r=ted (e671e7c651)
- Bug 1137000 - Add support for SDK building to moz-automation.mk. r=mshal (69b7ccb3c8)
- Bug 1175895 - aid greppability of MOZ_AUTOMATION_*; r=ted (c9a099f168)
- Bug 1198179 - Kill gen_mach_buildprops.py; r=ted (fa74e1930f)
- Bug 1198179 - make upload.py write properties even if not uploading; r=ted (e7ca79b807)
- Bug 8623031 - Move desktop build logic to a container neutral location; r=dustin (81dc866373)
- Bug 1187139 (part 1) - Replace nsBaseHashtable::Enumerate() calls in accessible/ with iterators. r=tbsaunde. (7a75c73d17)
- Bug 1187139 (part 2) - Replace nsBaseHashtable::Enumerate() calls in accessible/ with iterators. r=tbsaunde. (c631350ddb)
- Bug 1187139 (part 3) - Replace nsBaseHashtable::Enumerate() calls in accessible/ with iterators. r=tbsaunde. (052cced2ca)
- Bug 1225396 part 4 - Remove @@iterator workaround in Codegen.py. r=bz (3b05ddc4f0)
- Bug 1048695 part 1. Pass the set of globals where a member should NOT be exposed to MemberCondition. r=peterv (d5c9040323)
- Bug 1048695 part 2. Make interface members not be exposed based on their nonExposedGlobals. r=peterv (e852319bd0)
- Bug 1229493 - Stop shell-only modules classes being reported as standard classes r=shu (4a6457af8d)
- Bug 1151646 - Fix static analysis bustage. (347564b4d2)
- Bug 1231051 - Moz2Dify nsNativeThemeCocoa::DrawWidgetBackground. r=mstange. (cbcbe17e30)
- Bug 1178984 - Crashes at nsMenuBarX::RemoveMenuAtIndex. r=spohl (6e5869ae28)
- leftovers of Bug 1151345 - Add debug logging to help decipher this bug. r=spohl (22d42fc66d)

dom/fetch/FetchDriver.cpp

@@ -245,10 +245,8 @@ FetchDriver::HttpFetch()
   MOZ_ASSERT(mLoadGroup);
   nsCOMPtr<nsIChannel> chan;
 
-  // For dedicated workers mDocument refers to the parent document of the
-  // worker (why do we do that?). In that case we don't want to use the
-  // document here since that is not the correct principal.
-  if (mDocument && mDocument->NodePrincipal() == mPrincipal) {
+  if (mDocument) {
+    MOZ_ASSERT(mDocument->NodePrincipal() == mPrincipal);
     rv = NS_NewChannel(getter_AddRefs(chan),
                        uri,
                        mDocument,