--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -714,21 +714,35 @@ Gecko_CreateGradient(uint8_t aShape,
   }
 
   return result;
 }
 
 void
 Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity, size_t aElemSize)
 {
-  auto base = reinterpret_cast<nsTArray_base<nsTArrayInfallibleAllocator, nsTArray_CopyWithMemutils> *>(aArray);
+  auto base =
+    reinterpret_cast<nsTArray_base<nsTArrayInfallibleAllocator,
+                                   nsTArray_CopyWithMemutils> *>(aArray);
+
   base->EnsureCapacity<nsTArrayInfallibleAllocator>(aCapacity, aElemSize);
 }
 
 void
+Gecko_ClearPODTArray(void* aArray, size_t aElementSize, size_t aElementAlign)
+{
+  auto base =
+    reinterpret_cast<nsTArray_base<nsTArrayInfallibleAllocator,
+                                   nsTArray_CopyWithMemutils> *>(aArray);
+
+  base->template ShiftData<nsTArrayInfallibleAllocator>(0, base->Length(), 0,
+                                                        aElementSize, aElementAlign);
+}
+
+void
 Gecko_EnsureImageLayersLength(nsStyleImageLayers* aLayers, size_t aLen)
 {
   aLayers->mLayers.EnsureLengthAtLeast(aLen);
 }
 
 void
 Gecko_InitializeImageLayer(nsStyleImageLayers::Layer* aLayer,
                                 nsStyleImageLayers::LayerType aLayerType)

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -199,16 +199,21 @@ nsChangeHint Gecko_CalcStyleDifference(n
                                        ServoComputedValues* newstyle);
 void Gecko_StoreStyleDifference(RawGeckoNode* node, nsChangeHint change);
 
 // `array` must be an nsTArray
 // If changing this signature, please update the
 // friend function declaration in nsTArray.h
 void Gecko_EnsureTArrayCapacity(void* array, size_t capacity, size_t elem_size);
 
+// Same here, `array` must be an nsTArray<T>, for some T.
+//
+// Important note: Only valid for POD types, since destructors won't be run
+// otherwise. This is ensured with rust traits for the relevant structs.
+void Gecko_ClearPODTArray(void* array, size_t elem_size, size_t elem_align);
 
 void Gecko_EnsureImageLayersLength(nsStyleImageLayers* layers, size_t len);
 
 void Gecko_InitializeImageLayer(nsStyleImageLayers::Layer* layer,
                                 nsStyleImageLayers::LayerType layer_type);
 
 // Clean up pointer-based coordinates
 void Gecko_ResetStyleCoord(nsStyleUnit* unit, nsStyleUnion* value);

--- a/xpcom/glue/nsTArray.h
+++ b/xpcom/glue/nsTArray.h
@@ -323,32 +323,41 @@ struct nsTArray_SafeElementAtHelper<mozi
   {
     if (aIndex < static_cast<const Derived*>(this)->Length()) {
       return static_cast<const Derived*>(this)->ElementAt(aIndex);
     }
     return nullptr;
   }
 };
 
-extern "C" void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity, size_t aElemSize);
+// Servo bindings.
+extern "C" void Gecko_EnsureTArrayCapacity(void* aArray,
+                                           size_t aCapacity,
+                                           size_t aElementSize);
+extern "C" void Gecko_ClearPODTArray(void* aArray,
+                                     size_t aElementSize,
+                                     size_t aElementAlign);
 
 //
 // This class serves as a base class for nsTArray.  It shouldn't be used
 // directly.  It holds common implementation code that does not depend on the
 // element type of the nsTArray.
 //
 template<class Alloc, class Copy>
 class nsTArray_base
 {
   // Allow swapping elements with |nsTArray_base|s created using a
   // different allocator.  This is kosher because all allocators use
   // the same free().
   template<class Allocator, class Copier>
   friend class nsTArray_base;
-  friend void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity, size_t aElemSize);
+  friend void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity,
+                                         size_t aElemSize);
+  friend void Gecko_ClearPODTArray(void* aTArray, size_t aElementSize,
+                                   size_t aElementAlign);
 
 protected:
   typedef nsTArrayHeader Header;
 
 public:
   typedef size_t size_type;
   typedef size_t index_type;