diff --git a/accessible/src/base/nsCoreUtils.h b/accessible/src/base/nsCoreUtils.h
index 0bb683d9e658..3a348105e051 100644
--- a/accessible/src/base/nsCoreUtils.h
+++ b/accessible/src/base/nsCoreUtils.h
@@ -7,6 +7,7 @@
 #define nsCoreUtils_h_
 
 #include "nsIContent.h"
+#include "nsIDocument.h"
 #include "nsIPresShell.h"
 
 #include "nsIDOMDOMStringList.h"
diff --git a/content/base/public/Element.h b/content/base/public/Element.h
index 36795237aa0b..763e24dae6d2 100644
--- a/content/base/public/Element.h
+++ b/content/base/public/Element.h
@@ -17,6 +17,7 @@
 #include "nsChangeHint.h"                  // for enum
 #include "nsEventStates.h"                 // for member
 #include "mozilla/dom/DirectionalityUtils.h"
+#include "nsIDocument.h"
 #include "nsIDOMElement.h"
 #include "nsIDOMDocumentFragment.h"
 #include "nsILinkHandler.h"
diff --git a/content/base/public/moz.build b/content/base/public/moz.build
index 50bee3e689c9..59f0dc041c44 100644
--- a/content/base/public/moz.build
+++ b/content/base/public/moz.build
@@ -49,6 +49,7 @@ EXPORTS += [
     'nsHostObjectProtocolHandler.h',
     'nsIAttribute.h',
     'nsIContent.h',
+    'nsIContentInlines.h',
     'nsIContentIterator.h',
     'nsIContentSerializer.h',
     'nsIDocument.h',
diff --git a/content/base/public/nsIContent.h b/content/base/public/nsIContent.h
index e49ac3e3b74a..a81dd3f656e4 100644
--- a/content/base/public/nsIContent.h
+++ b/content/base/public/nsIContent.h
@@ -7,7 +7,7 @@
 
 #include "mozilla/Attributes.h"
 #include "nsCaseTreatment.h" // for enum, cannot be forward-declared
-#include "nsIDocument.h"
+#include "nsINode.h"
 
 // Forward declarations
 class nsAString;
@@ -243,10 +243,7 @@ public:
    * Return true iff this node is in an HTML document (in the HTML5 sense of
    * the term, i.e. not in an XHTML/XML document).
    */
-  inline bool IsInHTMLDocument() const
-  {
-    return OwnerDoc()->IsHTML();
-  }
+  inline bool IsInHTMLDocument() const;
 
   /**
    * Get the namespace that this element's tag is defined in
diff --git a/content/base/public/nsIContentInlines.h b/content/base/public/nsIContentInlines.h
new file mode 100644
index 000000000000..e4345cfce59f
--- /dev/null
+++ b/content/base/public/nsIContentInlines.h
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 8; -*- */
+/* vim: set sw=2 sts=2 ts=8 et tw=80 : */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIContentInlines_h
+#define nsIContentInlines_h
+
+#include "nsIContent.h"
+#include "nsIDocument.h"
+
+inline bool
+nsIContent::IsInHTMLDocument() const
+{
+  return OwnerDoc()->IsHTML();
+}
+
+#endif // nsIContentInlines_h
diff --git a/content/base/src/Attr.cpp b/content/base/src/Attr.cpp
index 9d5a18765061..dda97e482df8 100644
--- a/content/base/src/Attr.cpp
+++ b/content/base/src/Attr.cpp
@@ -16,6 +16,7 @@
 #include "nsError.h"
 #include "nsUnicharUtils.h"
 #include "nsDOMString.h"
+#include "nsIContentInlines.h"
 #include "nsIDocument.h"
 #include "nsIDOMDocument.h"
 #include "nsIDOMUserDataHandler.h"
diff --git a/content/base/src/Element.cpp b/content/base/src/Element.cpp
index 19da6cf77fd8..4586f8a96f8c 100644
--- a/content/base/src/Element.cpp
+++ b/content/base/src/Element.cpp
@@ -16,6 +16,7 @@
 #include "mozilla/dom/Attr.h"
 #include "nsDOMAttributeMap.h"
 #include "nsIAtom.h"
+#include "nsIContentInlines.h"
 #include "nsINodeInfo.h"
 #include "nsIDocumentInlines.h"
 #include "nsIDOMNodeList.h"
diff --git a/content/base/src/Link.h b/content/base/src/Link.h
index c805a07368e8..163bf746f7cb 100644
--- a/content/base/src/Link.h
+++ b/content/base/src/Link.h
@@ -13,6 +13,7 @@
 
 #include "mozilla/IHistory.h"
 #include "mozilla/MemoryReporting.h"
+#include "nsEventStates.h"
 #include "nsIContent.h"
 
 namespace mozilla {
diff --git a/content/base/src/nsDOMAttributeMap.cpp b/content/base/src/nsDOMAttributeMap.cpp
index bd7c5472f4c0..b7a0fe7911bf 100644
--- a/content/base/src/nsDOMAttributeMap.cpp
+++ b/content/base/src/nsDOMAttributeMap.cpp
@@ -16,6 +16,7 @@
 #include "nsAttrName.h"
 #include "nsContentUtils.h"
 #include "nsError.h"
+#include "nsIContentInlines.h"
 #include "nsIDocument.h"
 #include "nsIDOMDocument.h"
 #include "nsINameSpaceManager.h"
diff --git a/content/base/src/nsFrameLoader.cpp b/content/base/src/nsFrameLoader.cpp
index 31671f9b4fe3..275931f5bdc1 100644
--- a/content/base/src/nsFrameLoader.cpp
+++ b/content/base/src/nsFrameLoader.cpp
@@ -19,7 +19,7 @@
 #include "nsIDOMMozBrowserFrame.h"
 #include "nsIDOMWindow.h"
 #include "nsIPresShell.h"
-#include "nsIContent.h"
+#include "nsIContentInlines.h"
 #include "nsIContentViewer.h"
 #include "nsIDocument.h"
 #include "nsIDOMDocument.h"
diff --git a/content/base/src/nsNodeUtils.h b/content/base/src/nsNodeUtils.h
index d02d75d9e29b..e41c0d3221f5 100644
--- a/content/base/src/nsNodeUtils.h
+++ b/content/base/src/nsNodeUtils.h
@@ -9,6 +9,7 @@
 #include "nsIContent.h"          // for use in inline function (ParentChainChanged)
 #include "nsIMutationObserver.h" // for use in inline function (ParentChainChanged)
 #include "js/TypeDecls.h"
+#include "nsCOMArray.h"
 
 struct CharacterDataChangeInfo;
 class nsIVariant;
diff --git a/content/events/src/nsDOMDataTransfer.cpp b/content/events/src/nsDOMDataTransfer.cpp
index cf5b263f6578..59d7239b0a91 100644
--- a/content/events/src/nsDOMDataTransfer.cpp
+++ b/content/events/src/nsDOMDataTransfer.cpp
@@ -22,6 +22,8 @@
 #include "nsCRT.h"
 #include "nsIScriptObjectPrincipal.h"
 #include "nsIScriptContext.h"
+#include "nsIDocument.h"
+#include "nsIScriptGlobalObject.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
diff --git a/content/html/content/src/nsGenericHTMLElement.cpp b/content/html/content/src/nsGenericHTMLElement.cpp
index 3fb825ac8e4a..1b504e67da47 100644
--- a/content/html/content/src/nsGenericHTMLElement.cpp
+++ b/content/html/content/src/nsGenericHTMLElement.cpp
@@ -13,6 +13,7 @@
 #include "nsAttrValueInlines.h"
 #include "nsCOMPtr.h"
 #include "nsIAtom.h"
+#include "nsIContentInlines.h"
 #include "nsIContentViewer.h"
 #include "mozilla/css/StyleRule.h"
 #include "nsIDocument.h"
diff --git a/content/media/TextTrackCue.h b/content/media/TextTrackCue.h
index 8f3b8ef954a6..891e4e657bef 100644
--- a/content/media/TextTrackCue.h
+++ b/content/media/TextTrackCue.h
@@ -13,6 +13,7 @@
 #include "nsDOMEventTargetHelper.h"
 #include "nsIWebVTTParserWrapper.h"
 #include "mozilla/StaticPtr.h"
+#include "nsIDocument.h"
 
 namespace mozilla {
 namespace dom {
diff --git a/content/svg/content/src/nsSVGFeatures.cpp b/content/svg/content/src/nsSVGFeatures.cpp
index b22ad28eb59c..153a00cfdd1e 100644
--- a/content/svg/content/src/nsSVGFeatures.cpp
+++ b/content/svg/content/src/nsSVGFeatures.cpp
@@ -14,6 +14,7 @@
 
 #include "nsSVGFeatures.h"
 #include "nsIContent.h"
+#include "nsIDocument.h"
 #include "mozilla/Preferences.h"
 
 using namespace mozilla;
diff --git a/content/xbl/src/nsBindingManager.h b/content/xbl/src/nsBindingManager.h
index 099d8bb682e3..dd02b350ebdd 100644
--- a/content/xbl/src/nsBindingManager.h
+++ b/content/xbl/src/nsBindingManager.h
@@ -30,6 +30,7 @@ class nsXBLBinding;
 template<class E> class nsRefPtr;
 typedef nsTArray<nsRefPtr<nsXBLBinding> > nsBindingList;
 class nsIPrincipal;
+class nsCSSStyleSheet;
 
 class nsBindingManager MOZ_FINAL : public nsStubMutationObserver
 {
diff --git a/content/xslt/src/xpath/txXPathTreeWalker.h b/content/xslt/src/xpath/txXPathTreeWalker.h
index 41acf1343184..8f0e9d0a817b 100644
--- a/content/xslt/src/xpath/txXPathTreeWalker.h
+++ b/content/xslt/src/xpath/txXPathTreeWalker.h
@@ -8,6 +8,7 @@
 
 #include "txCore.h"
 #include "txXPathNode.h"
+#include "nsIContentInlines.h"
 #include "nsINodeInfo.h"
 #include "nsTArray.h"
 
diff --git a/content/xul/content/src/nsXULContextMenuBuilder.cpp b/content/xul/content/src/nsXULContextMenuBuilder.cpp
index 6317e5fb3b56..6e342aac3fb9 100644
--- a/content/xul/content/src/nsXULContextMenuBuilder.cpp
+++ b/content/xul/content/src/nsXULContextMenuBuilder.cpp
@@ -9,6 +9,7 @@
 #include "nsIDOMHTMLElement.h"
 #include "nsIDOMHTMLMenuItemElement.h"
 #include "nsXULContextMenuBuilder.h"
+#include "nsIDocument.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
diff --git a/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp b/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp
index 9207f55a0f05..3909840aebad 100644
--- a/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp
+++ b/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp
@@ -33,6 +33,7 @@
 #include "nsXULTemplateResultSetRDF.h"
 #include "nsXULTemplateQueryProcessorRDF.h"
 #include "nsXULSortService.h"
+#include "nsIDocument.h"
 
 //----------------------------------------------------------------------
 
diff --git a/content/xul/templates/src/nsXULTemplateQueryProcessorStorage.cpp b/content/xul/templates/src/nsXULTemplateQueryProcessorStorage.cpp
index 08467cac9223..6cfad39b57f6 100644
--- a/content/xul/templates/src/nsXULTemplateQueryProcessorStorage.cpp
+++ b/content/xul/templates/src/nsXULTemplateQueryProcessorStorage.cpp
@@ -25,6 +25,8 @@
 #include "nsXULSortService.h"
 
 #include "mozIStorageService.h"
+#include "nsIChannel.h"
+#include "nsIDocument.h"
 
 //----------------------------------------------------------------------
 //
diff --git a/dom/plugins/base/nsPluginInstanceOwner.cpp b/dom/plugins/base/nsPluginInstanceOwner.cpp
index 9666a75720c2..6a679b4150b8 100644
--- a/dom/plugins/base/nsPluginInstanceOwner.cpp
+++ b/dom/plugins/base/nsPluginInstanceOwner.cpp
@@ -59,6 +59,7 @@ using mozilla::DefaultXDisplay;
 #include "ImageContainer.h"
 #include "nsIDOMHTMLCollection.h"
 #include "GLContext.h"
+#include "nsIContentInlines.h"
 #include "mozilla/MiscEvents.h"
 #include "mozilla/MouseEvents.h"
 #include "mozilla/TextEvents.h"
diff --git a/layout/base/nsCSSFrameConstructor.h b/layout/base/nsCSSFrameConstructor.h
index 2332a983384b..930cc2c9e201 100644
--- a/layout/base/nsCSSFrameConstructor.h
+++ b/layout/base/nsCSSFrameConstructor.h
@@ -20,6 +20,7 @@
 #include "nsCSSPseudoElements.h"
 #include "nsIAnonymousContentCreator.h"
 #include "nsFrameManager.h"
+#include "nsIDocument.h"
 
 struct nsFrameItems;
 struct nsAbsoluteItems;
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 5bf8fb0a310a..52719046caa6 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -28,6 +28,7 @@
 
 #include "mozilla/Likely.h"
 #include "nsIURI.h"
+#include "nsIDocument.h"
 #include <algorithm>
 
 static_assert((((1 << nsStyleStructID_Length) - 1) &
diff --git a/layout/xul/base/public/nsXULPopupManager.h b/layout/xul/base/public/nsXULPopupManager.h
index 56739e81d009..db6485652d40 100644
--- a/layout/xul/base/public/nsXULPopupManager.h
+++ b/layout/xul/base/public/nsXULPopupManager.h
@@ -51,6 +51,7 @@ class nsMenuBarFrame;
 class nsMenuParent;
 class nsIDOMKeyEvent;
 class nsIDocShellTreeItem;
+class nsPIDOMWindow;
 
 // when a menu command is executed, the closemenu attribute may be used
 // to define how the menu should be closed up
diff --git a/parser/html/nsHtml5SVGLoadDispatcher.cpp b/parser/html/nsHtml5SVGLoadDispatcher.cpp
index 1a9186616010..07fa7b9e1056 100644
--- a/parser/html/nsHtml5SVGLoadDispatcher.cpp
+++ b/parser/html/nsHtml5SVGLoadDispatcher.cpp
@@ -7,6 +7,7 @@
 #include "nsEventDispatcher.h"
 #include "nsIPresShell.h"
 #include "mozilla/BasicEvents.h"
+#include "nsIDocument.h"
 
 using namespace mozilla;
 
diff --git a/widget/cocoa/nsCocoaUtils.mm b/widget/cocoa/nsCocoaUtils.mm
index c8696026cf9a..2ea2d1653e04 100644
--- a/widget/cocoa/nsCocoaUtils.mm
+++ b/widget/cocoa/nsCocoaUtils.mm
@@ -16,6 +16,7 @@
 #include "nsIServiceManager.h"
 #include "nsMenuUtilsX.h"
 #include "nsToolkit.h"
+#include "nsCRT.h"
 #include "mozilla/MiscEvents.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/TextEvents.h"