Auto merge of #15904 - sendilkumarn:image-area, r=jdm

making image element areas good at finding areas

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---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #15884

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2 files changed, 15 insertions, 10 deletions

diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index acf1d2ed9ce..7cebebade0a 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -429,16 +429,12 @@ impl HTMLImageElement {
             return None
         }
 
-        let map = self.upcast::<Node>()
-                      .following_siblings()
-                      .filter_map(Root::downcast::<HTMLMapElement>)
-                      .find(|n| n.upcast::<Element>().get_string_attribute(&LocalName::from("name")) == last);
-
-        let elements: Vec<Root<HTMLAreaElement>> = map.unwrap().upcast::<Node>()
-                      .children()
-                      .filter_map(Root::downcast::<HTMLAreaElement>)
-                      .collect();
-        Some(elements)
+        let useMapElements = document_from_node(self).upcast::<Node>()
+                                .traverse_preorder()
+                                .filter_map(Root::downcast::<HTMLMapElement>)
+                                .find(|n| n.upcast::<Element>().get_string_attribute(&LocalName::from("name")) == last);
+
+        useMapElements.map(|mapElem| mapElem.get_area_elements())
     }
 }
 
diff --git a/components/script/dom/htmlmapelement.rs b/components/script/dom/htmlmapelement.rs
index c6bcb615431..9a2ae807619 100644
--- a/components/script/dom/htmlmapelement.rs
+++ b/components/script/dom/htmlmapelement.rs
@@ -3,9 +3,11 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::Bindings::HTMLMapElementBinding;
+use dom::bindings::inheritance::Castable;
 use dom::bindings::js::Root;
 use dom::bindings::str::DOMString;
 use dom::document::Document;
+use dom::htmlareaelement::HTMLAreaElement;
 use dom::htmlelement::HTMLElement;
 use dom::node::Node;
 use dom_struct::dom_struct;
@@ -33,4 +35,11 @@ impl HTMLMapElement {
                            document,
                            HTMLMapElementBinding::Wrap)
     }
+
+    pub fn get_area_elements(&self) -> Vec<Root<HTMLAreaElement>> {
+        self.upcast::<Node>()
+            .traverse_preorder()
+            .filter_map(Root::downcast::<HTMLAreaElement>).collect()
+    }
 }
+