Bug 1328786 - Part 1: Add an FFI function for expanding nsStyleAutoArray. r=heycam

layout/style/ServoBindings.cpp

@@ -900,6 +900,15 @@ Gecko_EnsureImageLayersLength(nsStyleImageLayers* aLayers, size_t aLen,
   }
 }
 
+void
+Gecko_EnsureStyleAnimationArrayLength(void* aArray, size_t aLen)
+{
+  auto base =
+    reinterpret_cast<nsStyleAutoArray<StyleAnimation>*>(aArray);
+
+  base->EnsureLengthAtLeast(aLen);
+}
+
 void
 Gecko_ResetStyleCoord(nsStyleUnit* aUnit, nsStyleUnion* aValue)
 {

layout/style/ServoBindings.h

@@ -257,6 +257,8 @@ void Gecko_CopyStyleContentsFrom(nsStyleContent* content, const nsStyleContent*
 void Gecko_EnsureImageLayersLength(nsStyleImageLayers* layers, size_t len,
                                    nsStyleImageLayers::LayerType layer_type);
 
+void Gecko_EnsureStyleAnimationArrayLength(void* array, size_t len);
+
 // Clean up pointer-based coordinates
 void Gecko_ResetStyleCoord(nsStyleUnit* unit, nsStyleUnion* value);