diff --git a/dom/flex/Flex.cpp b/dom/flex/Flex.cpp
index 057f49cf3f4b..3183f1f28ff6 100644
--- a/dom/flex/Flex.cpp
+++ b/dom/flex/Flex.cpp
@@ -7,6 +7,7 @@
 #include "Flex.h"
 
 #include "FlexLineValues.h"
+#include "mozilla/dom/Element.h"
 #include "mozilla/dom/FlexBinding.h"
 #include "nsFlexContainerFrame.h"
 
diff --git a/dom/flex/FlexItemValues.cpp b/dom/flex/FlexItemValues.cpp
index fd7454cf0877..07465afc999a 100644
--- a/dom/flex/FlexItemValues.cpp
+++ b/dom/flex/FlexItemValues.cpp
@@ -6,7 +6,9 @@
 
 #include "FlexItemValues.h"
 
+#include "mozilla/dom/DOMRect.h"
 #include "mozilla/dom/FlexBinding.h"
+#include "mozilla/dom/FlexLineValues.h"
 #include "nsFlexContainerFrame.h"
 
 namespace mozilla {
diff --git a/dom/flex/FlexItemValues.h b/dom/flex/FlexItemValues.h
index bb152d9542d6..c775cdbcfa39 100644
--- a/dom/flex/FlexItemValues.h
+++ b/dom/flex/FlexItemValues.h
@@ -13,9 +13,13 @@
 
 struct ComputedFlexItemInfo;
 
+class nsINode;
+
 namespace mozilla {
 namespace dom {
 
+class DOMRectReadOnly;
+
 class FlexLineValues;
 
 class FlexItemValues : public nsISupports, public nsWrapperCache {
diff --git a/layout/base/LayoutConstants.h b/layout/base/LayoutConstants.h
index 21e85d5610da..c05a22077594 100644
--- a/layout/base/LayoutConstants.h
+++ b/layout/base/LayoutConstants.h
@@ -75,6 +75,12 @@ enum class ComputeSizeFlag : uint8_t {
 };
 using ComputeSizeFlags = mozilla::EnumSet<ComputeSizeFlag>;
 
+/**
+ * This is used in some nsLayoutUtils functions.
+ * Declared here so that fewer files need to include nsLayoutUtils.h.
+ */
+enum class IntrinsicISizeType { MinISize, PrefISize };
+
 }  // namespace mozilla
 
 #endif  // LayoutConstants_h___
diff --git a/layout/base/nsCSSFrameConstructor.h b/layout/base/nsCSSFrameConstructor.h
index ae8829d8fe63..b0c0c0755a38 100644
--- a/layout/base/nsCSSFrameConstructor.h
+++ b/layout/base/nsCSSFrameConstructor.h
@@ -30,6 +30,7 @@
 struct nsStyleDisplay;
 struct nsGenConInitializer;
 
+class nsBlockFrame;
 class nsContainerFrame;
 class nsFirstLineFrame;
 class nsFirstLetterFrame;
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 2e3b707b480f..cd93e0e69a10 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -5510,12 +5510,11 @@ static bool IsReplacedBoxResolvedAgainstZero(
  */
 static nscoord AddIntrinsicSizeOffset(
     gfxContext* aRenderingContext, nsIFrame* aFrame,
-    const nsIFrame::IntrinsicSizeOffsetData& aOffsets,
-    nsLayoutUtils::IntrinsicISizeType aType, StyleBoxSizing aBoxSizing,
-    nscoord aContentSize, nscoord aContentMinSize, const StyleSize& aStyleSize,
-    const nscoord* aFixedMinSize, const StyleSize& aStyleMinSize,
-    const nscoord* aFixedMaxSize, const StyleMaxSize& aStyleMaxSize,
-    uint32_t aFlags, PhysicalAxis aAxis) {
+    const nsIFrame::IntrinsicSizeOffsetData& aOffsets, IntrinsicISizeType aType,
+    StyleBoxSizing aBoxSizing, nscoord aContentSize, nscoord aContentMinSize,
+    const StyleSize& aStyleSize, const nscoord* aFixedMinSize,
+    const StyleSize& aStyleMinSize, const nscoord* aFixedMaxSize,
+    const StyleMaxSize& aStyleMaxSize, uint32_t aFlags, PhysicalAxis aAxis) {
   nscoord result = aContentSize;
   nscoord min = aContentMinSize;
   nscoord coordOutsideSize = 0;
diff --git a/layout/base/nsLayoutUtils.h b/layout/base/nsLayoutUtils.h
index 02d292c13fab..12e377392ba8 100644
--- a/layout/base/nsLayoutUtils.h
+++ b/layout/base/nsLayoutUtils.h
@@ -1555,9 +1555,8 @@ class nsLayoutUtils {
    * size by reducing the *content size* (flooring at zero).  This is used for:
    * https://drafts.csswg.org/css-grid/#min-size-auto
    */
-  enum class IntrinsicISizeType { MinISize, PrefISize };
-  static const auto MIN_ISIZE = IntrinsicISizeType::MinISize;
-  static const auto PREF_ISIZE = IntrinsicISizeType::PrefISize;
+  static const auto MIN_ISIZE = mozilla::IntrinsicISizeType::MinISize;
+  static const auto PREF_ISIZE = mozilla::IntrinsicISizeType::PrefISize;
   enum {
     IGNORE_PADDING = 0x01,
     BAIL_IF_REFLOW_NEEDED = 0x02,  // returns NS_INTRINSIC_ISIZE_UNKNOWN if so
@@ -1565,7 +1564,7 @@ class nsLayoutUtils {
   };
   static nscoord IntrinsicForAxis(
       mozilla::PhysicalAxis aAxis, gfxContext* aRenderingContext,
-      nsIFrame* aFrame, IntrinsicISizeType aType,
+      nsIFrame* aFrame, mozilla::IntrinsicISizeType aType,
       const mozilla::Maybe<LogicalSize>& aPercentageBasis = mozilla::Nothing(),
       uint32_t aFlags = 0, nscoord aMarginBoxMinSizeClamp = NS_MAXSIZE);
   /**
@@ -1573,7 +1572,7 @@ class nsLayoutUtils {
    */
   static nscoord IntrinsicForContainer(gfxContext* aRenderingContext,
                                        nsIFrame* aFrame,
-                                       IntrinsicISizeType aType,
+                                       mozilla::IntrinsicISizeType aType,
                                        uint32_t aFlags = 0);
 
   /**
@@ -1597,7 +1596,7 @@ class nsLayoutUtils {
    */
   static nscoord MinSizeContributionForAxis(mozilla::PhysicalAxis aAxis,
                                             gfxContext* aRC, nsIFrame* aFrame,
-                                            IntrinsicISizeType aType,
+                                            mozilla::IntrinsicISizeType aType,
                                             const LogicalSize& aPercentageBasis,
                                             uint32_t aFlags = 0);
 
diff --git a/layout/forms/nsComboboxControlFrame.cpp b/layout/forms/nsComboboxControlFrame.cpp
index 13d09b12b4db..76d4bcbe4015 100644
--- a/layout/forms/nsComboboxControlFrame.cpp
+++ b/layout/forms/nsComboboxControlFrame.cpp
@@ -723,8 +723,8 @@ nscoord nsComboboxControlFrame::DropDownButtonISize() {
   return presContext->DevPixelsToAppUnits(dropdownButtonSize.width);
 }
 
-nscoord nsComboboxControlFrame::GetIntrinsicISize(
-    gfxContext* aRenderingContext, nsLayoutUtils::IntrinsicISizeType aType) {
+nscoord nsComboboxControlFrame::GetIntrinsicISize(gfxContext* aRenderingContext,
+                                                  IntrinsicISizeType aType) {
   // get the scrollbar width, we'll use this later
   nscoord scrollbarWidth = 0;
   nsPresContext* presContext = PresContext();
diff --git a/layout/forms/nsComboboxControlFrame.h b/layout/forms/nsComboboxControlFrame.h
index 61b4363167fe..f7513d6adb6b 100644
--- a/layout/forms/nsComboboxControlFrame.h
+++ b/layout/forms/nsComboboxControlFrame.h
@@ -238,7 +238,7 @@ class nsComboboxControlFrame final : public nsBlockFrame,
 
   // Helper for GetMinISize/GetPrefISize
   nscoord GetIntrinsicISize(gfxContext* aRenderingContext,
-                            nsLayoutUtils::IntrinsicISizeType aType);
+                            mozilla::IntrinsicISizeType aType);
 
   class RedisplayTextEvent : public mozilla::Runnable {
    public:
diff --git a/layout/forms/nsFieldSetFrame.cpp b/layout/forms/nsFieldSetFrame.cpp
index b526ac1acfe5..16e3fef6be64 100644
--- a/layout/forms/nsFieldSetFrame.cpp
+++ b/layout/forms/nsFieldSetFrame.cpp
@@ -13,6 +13,7 @@
 #include "mozilla/Likely.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/webrender/WebRenderAPI.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsCSSFrameConstructor.h"
 #include "nsCSSRendering.h"
@@ -340,8 +341,8 @@ image::ImgDrawResult nsFieldSetFrame::PaintBorder(
   return result;
 }
 
-nscoord nsFieldSetFrame::GetIntrinsicISize(
-    gfxContext* aRenderingContext, nsLayoutUtils::IntrinsicISizeType aType) {
+nscoord nsFieldSetFrame::GetIntrinsicISize(gfxContext* aRenderingContext,
+                                           IntrinsicISizeType aType) {
   nscoord legendWidth = 0;
   nscoord contentWidth = 0;
   if (!StyleDisplay()->IsContainSize()) {
diff --git a/layout/forms/nsFieldSetFrame.h b/layout/forms/nsFieldSetFrame.h
index b664097729e8..2d62aa89259c 100644
--- a/layout/forms/nsFieldSetFrame.h
+++ b/layout/forms/nsFieldSetFrame.h
@@ -21,7 +21,7 @@ class nsFieldSetFrame final : public nsContainerFrame {
   explicit nsFieldSetFrame(ComputedStyle* aStyle, nsPresContext* aPresContext);
 
   nscoord GetIntrinsicISize(gfxContext* aRenderingContext,
-                            nsLayoutUtils::IntrinsicISizeType);
+                            mozilla::IntrinsicISizeType);
   virtual nscoord GetMinISize(gfxContext* aRenderingContext) override;
   virtual nscoord GetPrefISize(gfxContext* aRenderingContext) override;
 
diff --git a/layout/generic/nsContainerFrame.cpp b/layout/generic/nsContainerFrame.cpp
index a16678b31e63..9efc026ff3be 100644
--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -11,6 +11,8 @@
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/dom/HTMLSummaryElement.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/Types.h"
 #include "nsAbsoluteContainingBlock.h"
 #include "nsAttrValue.h"
 #include "nsAttrValueInlines.h"
@@ -37,12 +39,19 @@
 #include "mozilla/AutoRestore.h"
 #include "nsIFrameInlines.h"
 #include "nsPrintfCString.h"
+#include "mozilla/webrender/WebRenderAPI.h"
 #include <algorithm>
 
 using namespace mozilla;
 using namespace mozilla::dom;
 using namespace mozilla::layout;
 
+using mozilla::gfx::ColorPattern;
+using mozilla::gfx::DeviceColor;
+using mozilla::gfx::Rect;
+using mozilla::gfx::sRGBColor;
+using mozilla::gfx::ToDeviceColor;
+
 nsContainerFrame::~nsContainerFrame() = default;
 
 NS_QUERYFRAME_HEAD(nsContainerFrame)
@@ -873,9 +882,9 @@ static nscoord GetCoord(const LengthPercentageOrAuto& aCoord,
   return GetCoord(aCoord.AsLengthPercentage(), aIfNotCoord);
 }
 
-void nsContainerFrame::DoInlineIntrinsicISize(
-    gfxContext* aRenderingContext, InlineIntrinsicISizeData* aData,
-    nsLayoutUtils::IntrinsicISizeType aType) {
+void nsContainerFrame::DoInlineIntrinsicISize(gfxContext* aRenderingContext,
+                                              InlineIntrinsicISizeData* aData,
+                                              IntrinsicISizeType aType) {
   if (GetPrevInFlow()) return;  // Already added.
 
   MOZ_ASSERT(
diff --git a/layout/generic/nsContainerFrame.h b/layout/generic/nsContainerFrame.h
index bcf508c75cb2..fd0dfcf01270 100644
--- a/layout/generic/nsContainerFrame.h
+++ b/layout/generic/nsContainerFrame.h
@@ -10,9 +10,9 @@
 #define nsContainerFrame_h___
 
 #include "mozilla/Attributes.h"
+#include "LayoutConstants.h"
 #include "nsSplittableFrame.h"
 #include "nsFrameList.h"
-#include "nsLayoutUtils.h"
 #include "nsLineBox.h"
 
 class nsOverflowContinuationTracker;
@@ -213,7 +213,7 @@ class nsContainerFrame : public nsSplittableFrame {
   // Used by both nsInlineFrame and nsFirstLetterFrame.
   void DoInlineIntrinsicISize(gfxContext* aRenderingContext,
                               InlineIntrinsicISizeData* aData,
-                              nsLayoutUtils::IntrinsicISizeType aType);
+                              mozilla::IntrinsicISizeType aType);
 
   /**
    * This is the CSS block concept of computing 'auto' widths, which most
diff --git a/layout/generic/nsFirstLetterFrame.cpp b/layout/generic/nsFirstLetterFrame.cpp
index dc2f165e7fe1..82f93f9193ae 100644
--- a/layout/generic/nsFirstLetterFrame.cpp
+++ b/layout/generic/nsFirstLetterFrame.cpp
@@ -15,6 +15,7 @@
 #include "mozilla/RestyleManager.h"
 #include "mozilla/ServoStyleSet.h"
 #include "nsIContent.h"
+#include "nsLayoutUtils.h"
 #include "nsLineLayout.h"
 #include "nsGkAtoms.h"
 #include "nsFrameManager.h"
diff --git a/layout/generic/nsFlexContainerFrame.cpp b/layout/generic/nsFlexContainerFrame.cpp
index e6824d6f4cb7..c1cf5e4d255d 100644
--- a/layout/generic/nsFlexContainerFrame.cpp
+++ b/layout/generic/nsFlexContainerFrame.cpp
@@ -5545,8 +5545,8 @@ void nsFlexContainerFrame::ReflowPlaceholders(
   }
 }
 
-nscoord nsFlexContainerFrame::IntrinsicISize(
-    gfxContext* aRenderingContext, nsLayoutUtils::IntrinsicISizeType aType) {
+nscoord nsFlexContainerFrame::IntrinsicISize(gfxContext* aRenderingContext,
+                                             IntrinsicISizeType aType) {
   nscoord containerISize = 0;
   const nsStylePosition* stylePos = StylePosition();
   const FlexboxAxisTracker axisTracker(this);
diff --git a/layout/generic/nsFlexContainerFrame.h b/layout/generic/nsFlexContainerFrame.h
index 032893c105fb..9c4a82f3b59f 100644
--- a/layout/generic/nsFlexContainerFrame.h
+++ b/layout/generic/nsFlexContainerFrame.h
@@ -644,7 +644,7 @@ class nsFlexContainerFrame final : public nsContainerFrame {
    * Helper for GetMinISize / GetPrefISize.
    */
   nscoord IntrinsicISize(gfxContext* aRenderingContext,
-                         nsLayoutUtils::IntrinsicISizeType aType);
+                         mozilla::IntrinsicISizeType aType);
 
   /**
    * Cached values to optimize GetMinISize/GetPrefISize.
diff --git a/layout/generic/nsGridContainerFrame.cpp b/layout/generic/nsGridContainerFrame.cpp
index b3812b12e6a2..593a28514241 100644
--- a/layout/generic/nsGridContainerFrame.cpp
+++ b/layout/generic/nsGridContainerFrame.cpp
@@ -42,7 +42,6 @@ using namespace mozilla;
 typedef nsAbsoluteContainingBlock::AbsPosReflowFlags AbsPosReflowFlags;
 typedef nsGridContainerFrame::TrackSize TrackSize;
 typedef mozilla::CSSAlignUtils::AlignJustifyFlags AlignJustifyFlags;
-typedef nsLayoutUtils::IntrinsicISizeType IntrinsicISizeType;
 
 using GridTemplate = StyleGridTemplateComponent;
 using TrackListValue =
diff --git a/layout/generic/nsGridContainerFrame.h b/layout/generic/nsGridContainerFrame.h
index eacde6b2ba95..b207bed9e4b8 100644
--- a/layout/generic/nsGridContainerFrame.h
+++ b/layout/generic/nsGridContainerFrame.h
@@ -313,7 +313,6 @@ class nsGridContainerFrame final : public nsContainerFrame {
   typedef mozilla::LogicalRect LogicalRect;
   typedef mozilla::LogicalSize LogicalSize;
   typedef mozilla::WritingMode WritingMode;
-  typedef nsLayoutUtils::IntrinsicISizeType IntrinsicISizeType;
   struct Grid;
   struct GridArea;
   class LineNameMap;
@@ -363,7 +362,7 @@ class nsGridContainerFrame final : public nsContainerFrame {
    * Helper for GetMinISize / GetPrefISize.
    */
   nscoord IntrinsicISize(gfxContext* aRenderingContext,
-                         IntrinsicISizeType aConstraint);
+                         mozilla::IntrinsicISizeType aConstraint);
 
   bool GetBBaseline(BaselineSharingGroup aBaselineGroup,
                     nscoord* aResult) const {
diff --git a/layout/svg/SVGGradientFrame.cpp b/layout/svg/SVGGradientFrame.cpp
index 724083b62e59..42116a985125 100644
--- a/layout/svg/SVGGradientFrame.cpp
+++ b/layout/svg/SVGGradientFrame.cpp
@@ -11,6 +11,7 @@
 // Keep others in (case-insensitive) order:
 #include "AutoReferenceChainGuard.h"
 #include "gfxPattern.h"
+#include "gfxUtils.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/SVGObserverUtils.h"
 #include "mozilla/SVGUtils.h"
diff --git a/layout/tables/nsTableWrapperFrame.cpp b/layout/tables/nsTableWrapperFrame.cpp
index c8d0561567cd..abc473a06934 100644
--- a/layout/tables/nsTableWrapperFrame.cpp
+++ b/layout/tables/nsTableWrapperFrame.cpp
@@ -340,7 +340,7 @@ nscoord nsTableWrapperFrame::GetPrefISize(gfxContext* aRenderingContext) {
         maxISize += capMin;
       } break;
       default: {
-        nsLayoutUtils::IntrinsicISizeType iwt;
+        IntrinsicISizeType iwt;
         if (captionSide == NS_STYLE_CAPTION_SIDE_TOP ||
             captionSide == NS_STYLE_CAPTION_SIDE_BOTTOM) {
           // Don't let the caption's pref isize expand the table's pref
diff --git a/layout/xul/nsBox.cpp b/layout/xul/nsBox.cpp
index 1371f74f0b42..cd36a2dea8d9 100644
--- a/layout/xul/nsBox.cpp
+++ b/layout/xul/nsBox.cpp
@@ -19,6 +19,7 @@
 #include "nsGkAtoms.h"
 #include "nsITheme.h"
 #include "nsBoxLayout.h"
+#include "nsLayoutUtils.h"
 #include "FrameLayerBuilder.h"
 #include "mozilla/dom/Attr.h"
 #include "mozilla/dom/Element.h"