--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -1458,44 +1458,36 @@ static bool AttrMatchesValue(const nsAtt
       return false;
   }
 }
 
 static inline bool
 edgeChildMatches(Element* aElement, TreeMatchContext& aTreeMatchContext,
                  bool checkFirst, bool checkLast)
 {
-  nsIContent *parent = aElement->GetParent();
-  if (!parent) {
-    return false;
-  }
-
-  if (aTreeMatchContext.mForStyling)
+  nsIContent* parent = aElement->GetParent();
+  if (parent && aTreeMatchContext.mForStyling)
     parent->SetFlags(NODE_HAS_EDGE_CHILD_SELECTOR);
 
   return (!checkFirst ||
           aTreeMatchContext.mNthIndexCache.
             GetNthIndex(aElement, false, false, true) == 1) &&
          (!checkLast ||
           aTreeMatchContext.mNthIndexCache.
             GetNthIndex(aElement, false, true, true) == 1);
 }
 
 static inline bool
 nthChildGenericMatches(Element* aElement,
                        TreeMatchContext& aTreeMatchContext,
                        nsPseudoClassList* pseudoClass,
                        bool isOfType, bool isFromEnd)
 {
-  nsIContent *parent = aElement->GetParent();
-  if (!parent) {
-    return false;
-  }
-
-  if (aTreeMatchContext.mForStyling) {
+  nsIContent* parent = aElement->GetParent();
+  if (parent && aTreeMatchContext.mForStyling) {
     if (isFromEnd)
       parent->SetFlags(NODE_HAS_SLOW_SELECTOR);
     else
       parent->SetFlags(NODE_HAS_SLOW_SELECTOR_LATER_SIBLINGS);
   }
 
   const int32_t index = aTreeMatchContext.mNthIndexCache.
     GetNthIndex(aElement, isOfType, isFromEnd, false);
@@ -1522,21 +1514,17 @@ nthChildGenericMatches(Element* aElement
          a * n == indexMinusB;
 }
 
 static inline bool
 edgeOfTypeMatches(Element* aElement, TreeMatchContext& aTreeMatchContext,
                   bool checkFirst, bool checkLast)
 {
   nsIContent *parent = aElement->GetParent();
-  if (!parent) {
-    return false;
-  }
-
-  if (aTreeMatchContext.mForStyling) {
+  if (parent && aTreeMatchContext.mForStyling) {
     if (checkLast)
       parent->SetFlags(NODE_HAS_SLOW_SELECTOR);
     else
       parent->SetFlags(NODE_HAS_SLOW_SELECTOR_LATER_SIBLINGS);
   }
 
   return (!checkFirst ||
           aTreeMatchContext.mNthIndexCache.
@@ -1938,17 +1926,17 @@ static bool SelectorMatches(Element* aEl
 
       case CSSPseudoClassType::lastNode:
         {
           nsIContent *lastNode = nullptr;
           nsIContent *parent = aElement->GetParent();
           if (parent) {
             if (aTreeMatchContext.mForStyling)
               parent->SetFlags(NODE_HAS_EDGE_CHILD_SELECTOR);
-            
+
             uint32_t index = parent->GetChildCount();
             do {
               lastNode = parent->GetChildAt(--index);
               // stop at first non-comment and non-whitespace node
             } while (lastNode &&
                      !IsSignificantChild(lastNode, true, false));
           }
           if (aElement != lastNode) {

--- a/layout/style/nsNthIndexCache.cpp
+++ b/layout/style/nsNthIndexCache.cpp
@@ -68,42 +68,40 @@ nsNthIndexCache::IndexDeterminedFromPrev
 
   return false;
 }
 
 int32_t
 nsNthIndexCache::GetNthIndex(Element* aChild, bool aIsOfType,
                              bool aIsFromEnd, bool aCheckEdgeOnly)
 {
-  NS_ASSERTION(aChild->GetParent(), "caller should check GetParent()");
-
   if (aChild->IsRootOfAnonymousSubtree()) {
     return 0;
   }
 
-  Cache &cache = mCaches[aIsOfType][aIsFromEnd];
+  Cache& cache = mCaches[aIsOfType][aIsFromEnd];
 
   if (!cache.initialized() && !cache.init()) {
     // Give up and just don't match.
     return 0;
   }
 
   Cache::AddPtr entry = cache.lookupForAdd(aChild);
 
   // Default the value to -2 when adding
   if (!entry && !cache.add(entry, aChild, -2)) {
     // No good; don't match.
     return 0;
   }
 
-  int32_t &slot = entry->value();
+  int32_t& slot = entry->value();
   if (slot != -2 && (slot != -1 || aCheckEdgeOnly)) {
     return slot;
   }
-  
+
   int32_t result = 1;
   if (aCheckEdgeOnly) {
     // The caller only cares whether or not the result is 1, so we can
     // stop as soon as we see any other elements that match us.
     if (aIsFromEnd) {
       for (nsIContent *cur = aChild->GetNextSibling();
            cur;
            cur = cur->GetNextSibling()) {