Bug 1468590: Preemptively fix unified build bustage in layout/base. r=emilio

This commit just adds some #include directives and "using namespace" directives.

(The "using namespace mozilla::dom;" are the important namespace directives
here, though I've included "using namespace mozilla;" alongside it as well, for
completeness/consistency.)

Differential Revision: https://phabricator.services.mozilla.com/D1647

layout/base/AccessibleCaretEventHub.cpp

@@ -25,6 +25,9 @@
 #include "nsITimer.h"
 #include "nsPresContext.h"
 
+using namespace mozilla;
+using namespace mozilla::dom;
+
 namespace mozilla {
 
 #undef AC_LOG

layout/base/PositionedEventTargeting.cpp

@@ -23,6 +23,9 @@
 #include <algorithm>
 #include "LayersLogging.h"
 
+using namespace mozilla;
+using namespace mozilla::dom;
+
 // If debugging this code you may wish to enable this logging, and also
 // uncomment the DumpFrameTree call near the bottom of the file.
 #define PET_LOG(...)

layout/base/ShapeUtils.h

@@ -10,6 +10,7 @@
 #include "nsCoord.h"
 #include "nsSize.h"
 #include "nsStyleConsts.h"
+#include "nsTArray.h"
 
 struct nsPoint;
 struct nsRect;

layout/base/nsLayoutUtils.cpp

@@ -69,6 +69,7 @@
 #include <algorithm>
 #include <limits>
 #include "mozilla/dom/AnonymousContent.h"
+#include "mozilla/dom/HTMLBodyElement.h"
 #include "mozilla/dom/HTMLMediaElementBinding.h"
 #include "mozilla/dom/HTMLVideoElement.h"
 #include "mozilla/dom/HTMLImageElement.h"