Remove the HashMap in RenderLayerCompositor's overlap map

LayoutTests/compositing/layer-creation/overlap-transformed-layer-with-transform-body-expected.txt

Index: LayoutTests/compositing/layer-creation/overlap-transformed-layer-with-transform-body-expected.txt
diff --git a/LayoutTests/compositing/layer-creation/overlap-transformed-layer-with-transform-body-expected.txt b/LayoutTests/compositing/layer-creation/overlap-transformed-layer-with-transform-body-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..5159fc59e131a83923a661a4e1ac50facec95b32
--- /dev/null
+++ b/LayoutTests/compositing/layer-creation/overlap-transformed-layer-with-transform-body-expected.txt
@@ -0,0 +1,37 @@
+(GraphicsLayer
+  (bounds 800.00 600.00)
+  (children 1
+    (GraphicsLayer
+      (bounds 800.00 600.00)
+      (contentsOpaque 1)
+      (drawsContent 1)
+      (children 1
+        (GraphicsLayer
+          (position 8.00 8.00)
+          (bounds 784.00 584.00)
+          (drawsContent 1)
+          (children 2
+            (GraphicsLayer
+              (position 15.00 0.00)
+              (anchor 1.47 0.00)
+              (bounds 256.00 256.00)
+              (contentsOpaque 1)
+              (drawsContent 1)
+              (transform [1.00 0.00 0.00 0.00] [0.00 1.00 0.00 0.00] [0.00 0.00 1.00 0.00] [-10.00 0.00 0.00 1.00])
+              (children 1
+                (GraphicsLayer
+                  (position 385.00 0.00)
+                )
+              )
+            )
+            (GraphicsLayer
+              (bounds 300.00 300.00)
+              (contentsOpaque 1)
+            )
+          )
+        )
+      )
+    )
+  )
+)
+