Auto merge of #8260 - martiansideofthemoon:my-code-fix, r=Manishearth

Implementing activation behavior for <label>

Attempt to resolve #8179 
@Manishearth , could you give me some resources having more information about what each function in `Activatable` does? The code compiles on my machine but I guess a lot more is needed

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components/script/dom/element.rs

@@ -43,6 +43,7 @@ use dom::htmlfieldsetelement::HTMLFieldSetElement;
 use dom::htmlfontelement::HTMLFontElement;
 use dom::htmliframeelement::HTMLIFrameElement;
 use dom::htmlinputelement::{HTMLInputElement, RawLayoutHTMLInputElementHelpers};
+use dom::htmllabelelement::HTMLLabelElement;
 use dom::htmllegendelement::HTMLLegendElement;
 use dom::htmloptgroupelement::HTMLOptGroupElement;
 use dom::htmltablecellelement::{HTMLTableCellElement, HTMLTableCellElementLayoutHelpers};
@@ -1719,6 +1720,10 @@ impl Element {
                 let element = self.downcast::<HTMLAnchorElement>().unwrap();
                 Some(element as &Activatable)
             },
+            NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLLabelElement)) => {
+                let element = self.downcast::<HTMLLabelElement>().unwrap();
+                Some(element as &Activatable)
+            },
             _ => {
                 None
             }

components/script/dom/htmllabelelement.rs

@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::activation::Activatable;
 use dom::attr::AttrValue;
 use dom::bindings::codegen::Bindings::HTMLLabelElementBinding;
 use dom::bindings::codegen::Bindings::HTMLLabelElementBinding::HTMLLabelElementMethods;
@@ -9,6 +10,8 @@ use dom::bindings::conversions::Castable;
 use dom::bindings::js::Root;
 use dom::document::Document;
 use dom::element::Element;
+use dom::event::Event;
+use dom::eventtarget::EventTarget;
 use dom::htmlelement::HTMLElement;
 use dom::htmlformelement::{FormControl, HTMLFormElement};
 use dom::node::{document_from_node, Node};
@@ -40,6 +43,40 @@ impl HTMLLabelElement {
     }
 }
 
+impl Activatable for HTMLLabelElement {
+    fn as_element(&self) -> &Element {
+        self.upcast::<Element>()
+    }
+
+    fn is_instance_activatable(&self) -> bool {
+        return true;
+    }
+
+    // https://html.spec.whatwg.org/multipage/#run-pre-click-activation-steps
+    // https://html.spec.whatwg.org/multipage/#the-button-element:activation-behavior
+    fn pre_click_activation(&self) {
+    }
+
+    // https://html.spec.whatwg.org/multipage/#run-canceled-activation-steps
+    fn canceled_activation(&self) {
+    }
+
+    // https://html.spec.whatwg.org/multipage/#run-post-click-activation-steps
+    fn activation_behavior(&self, _event: &Event, _target: &EventTarget) {
+        self.upcast::<Element>()
+            .as_maybe_activatable()
+            .map(|a| a.synthetic_click_activation(false, false, false, false));
+    }
+
+    // https://html.spec.whatwg.org/multipage/#implicit-submission
+    fn implicit_submission(&self, ctrlKey: bool, shiftKey: bool, altKey: bool, metaKey: bool) {
+        //FIXME: Investigate and implement implicit submission for label elements
+        // Issue filed at https://github.com/servo/servo/issues/8263
+    }
+
+
+}
+
 impl HTMLLabelElementMethods for HTMLLabelElement {
     // https://html.spec.whatwg.org/multipage/#dom-fae-form
     fn GetForm(&self) -> Option<Root<HTMLFormElement>> {