--- a/layout/style/GeckoStyleContext.cpp
+++ b/layout/style/GeckoStyleContext.cpp
@@ -22,16 +22,19 @@ GeckoStyleContext::GeckoStyleContext(nsS
                                      CSSPseudoElementType aPseudoType,
                                      already_AddRefed<nsRuleNode> aRuleNode,
                                      bool aSkipParentDisplayBasedStyleFixup)
   : nsStyleContext(aParent, aPseudoTag, aPseudoType)
   , mCachedResetData(nullptr)
   , mChild(nullptr)
   , mEmptyChild(nullptr)
   , mRuleNode(Move(aRuleNode))
+#ifdef DEBUG
+  , mComputingStruct(nsStyleStructID_None)
+#endif
 {
   mBits |= NS_STYLE_CONTEXT_IS_GECKO;
 
   if (aParent) {
 #ifdef DEBUG
     nsRuleNode *r1 = mParent->RuleNode(), *r2 = mRuleNode;
     while (r1->GetParent())
       r1 = r1->GetParent();

--- a/layout/style/GeckoStyleContext.h
+++ b/layout/style/GeckoStyleContext.h
@@ -186,12 +186,46 @@ private:
   // mChild for other children.  The order of children is not
   // meaningful.
   GeckoStyleContext* mChild;
   GeckoStyleContext* mEmptyChild;
   GeckoStyleContext* mPrevSibling;
   GeckoStyleContext* mNextSibling;
   RefPtr<nsRuleNode> mRuleNode;
 
+#ifdef DEBUG
+public:
+  struct AutoCheckDependency {
+
+    GeckoStyleContext* mStyleContext;
+    nsStyleStructID mOuterSID;
+
+    AutoCheckDependency(GeckoStyleContext* aContext, nsStyleStructID aInnerSID)
+      : mStyleContext(aContext)
+    {
+      mOuterSID = aContext->mComputingStruct;
+      MOZ_ASSERT(mOuterSID == nsStyleStructID_None ||
+                 DependencyAllowed(mOuterSID, aInnerSID),
+                 "Undeclared dependency, see generate-stylestructlist.py");
+      aContext->mComputingStruct = aInnerSID;
+    }
+
+    ~AutoCheckDependency()
+    {
+      mStyleContext->mComputingStruct = mOuterSID;
+    }
+
+  };
+
+private:
+  // Used to check for undeclared dependencies.
+  // See AUTO_CHECK_DEPENDENCY in nsStyleContextInlines.h.
+  nsStyleStructID         mComputingStruct;
+
+#define AUTO_CHECK_DEPENDENCY(gecko_, sid_) \
+  mozilla::GeckoStyleContext::AutoCheckDependency checkNesting_(gecko_, sid_)
+#else
+#define AUTO_CHECK_DEPENDENCY(gecko_, sid_)
+#endif
 };
 }
 
 #endif // mozilla_GeckoStyleContext_h

--- a/layout/style/nsStyleContext.cpp
+++ b/layout/style/nsStyleContext.cpp
@@ -85,17 +85,16 @@ nsStyleContext::nsStyleContext(nsStyleCo
                                nsIAtom* aPseudoTag,
                                CSSPseudoElementType aPseudoType)
   : mParent(aParent)
   , mPseudoTag(aPseudoTag)
   , mBits(((uint64_t)aPseudoType) << NS_STYLE_CONTEXT_TYPE_SHIFT)
   , mRefCnt(0)
 #ifdef DEBUG
   , mFrameRefCnt(0)
-  , mComputingStruct(nsStyleStructID_None)
 #endif
 {}
 
 void
 nsStyleContext::FinishConstruction()
 {
   // This check has to be done "backward", because if it were written the
   // more natural way it wouldn't fail even when it needed to.

--- a/layout/style/nsStyleContext.h
+++ b/layout/style/nsStyleContext.h
@@ -414,45 +414,16 @@ protected:
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
       default:
         MOZ_ASSERT_UNREACHABLE("unexpected nsStyleStructID value");
         return nullptr;
     }
   }
 
-#ifdef DEBUG
-  struct AutoCheckDependency {
-
-    nsStyleContext* mStyleContext;
-    nsStyleStructID mOuterSID;
-
-    AutoCheckDependency(nsStyleContext* aContext, nsStyleStructID aInnerSID)
-      : mStyleContext(aContext)
-    {
-      mOuterSID = aContext->mComputingStruct;
-      MOZ_ASSERT(mOuterSID == nsStyleStructID_None ||
-                 DependencyAllowed(mOuterSID, aInnerSID),
-                 "Undeclared dependency, see generate-stylestructlist.py");
-      aContext->mComputingStruct = aInnerSID;
-    }
-
-    ~AutoCheckDependency()
-    {
-      mStyleContext->mComputingStruct = mOuterSID;
-    }
-
-  };
-
-#define AUTO_CHECK_DEPENDENCY(sid_) \
-  AutoCheckDependency checkNesting_(this, sid_)
-#else
-#define AUTO_CHECK_DEPENDENCY(sid_)
-#endif
-
   // Helper functions for GetStyle* and PeekStyle*
   #define STYLE_STRUCT_INHERITED(name_, checkdata_cb_)                  \
     template<bool aComputeData>                                         \
     const nsStyle##name_ * DoGetStyle##name_();
   #define STYLE_STRUCT_RESET(name_, checkdata_cb_)                      \
     template<bool aComputeData>                                         \
     const nsStyle##name_ * DoGetStyle##name_();
 
@@ -480,18 +451,16 @@ protected:
   uint64_t                mBits;
 
   uint32_t                mRefCnt;
 
 #ifdef DEBUG
   uint32_t                mFrameRefCnt; // number of frames that use this
                                         // as their style context
 
-  nsStyleStructID         mComputingStruct;
-
   static bool DependencyAllowed(nsStyleStructID aOuterSID,
                                 nsStyleStructID aInnerSID)
   {
     return !!(sDependencyTable[aOuterSID] &
               nsCachedStyleData::GetBitForSID(aInnerSID));
   }
 
   static const uint32_t sDependencyTable[];

--- a/layout/style/nsStyleContextInlines.h
+++ b/layout/style/nsStyleContextInlines.h
@@ -67,17 +67,17 @@ const nsStyle##name_ * nsStyleContext::D
     if (cachedData) /* Have it cached already, yay */               \
       return cachedData;                                            \
     if (!aComputeData) {                                            \
       /* We always cache inherited structs on the context when we */\
       /* compute them. */                                           \
       return nullptr;                                               \
     }                                                               \
     /* Have the rulenode deal */                                    \
-    AUTO_CHECK_DEPENDENCY(eStyleStruct_##name_);                    \
+    AUTO_CHECK_DEPENDENCY(gecko, eStyleStruct_##name_);             \
     const nsStyle##name_ * newData =                                \
       gecko->RuleNode()->                                           \
         GetStyle##name_<aComputeData>(this->AsGecko(), mBits);      \
     /* always cache inherited data on the style context; the rule */\
     /* node set the bit in mBits for us if needed. */               \
     gecko->mCachedInheritedData                                     \
       .mStyleStructs[eStyleStruct_##name_] =                        \
       const_cast<nsStyle##name_ *>(newData);                        \
@@ -137,17 +137,17 @@ const nsStyle##name_ * nsStyleContext::D
     if (gecko->mCachedResetData) {                                            \
       const nsStyle##name_ * cachedData =                                     \
         static_cast<nsStyle##name_*>(                                         \
           gecko->mCachedResetData->mStyleStructs[eStyleStruct_##name_]);      \
       if (cachedData) /* Have it cached already, yay */                       \
         return cachedData;                                                    \
     }                                                                         \
     /* Have the rulenode deal */                                              \
-    AUTO_CHECK_DEPENDENCY(eStyleStruct_##name_);                              \
+    AUTO_CHECK_DEPENDENCY(gecko, eStyleStruct_##name_);                              \
     return gecko->RuleNode()->GetStyle##name_<aComputeData>(this->AsGecko()); \
   }                                                                           \
   auto servo = AsServo();                                                     \
   const bool needToCompute = !(mBits & NS_STYLE_INHERIT_BIT(name_));          \
   if (!aComputeData && needToCompute) {                                       \
     return nullptr;                                                           \
   }                                                                           \
   const nsStyle##name_* data =                                                \