Elements tab support for iOS Chrome DevTools (#4930)

* add initial implementation of the dom agent for ios

* add implementation of the css agent for ios

* refactor devtools inspector methods to somewhat accomodate ios and android

patch elements dom-node tests to test for ios too

* fix android dom-node test

* fix ios dom-node-tests to mock the ios devtools inspector properly

* fix: minor changes

tns-core-modules/debugger/devtools-elements.android.ts

@@ -0,0 +1,30 @@
+import { InspectorEvents, InspectorCommands } from "./devtools-elements";
+import { getDocument, getComputedStylesForNode, removeNode, setAttributeAsText } from "./devtools-elements.common";
+import { registerInspectorEvents, DOMNode } from "./dom-node";
+
+export function attachDOMInspectorEventCallbacks(DOMDomainFrontend: InspectorEvents) {
+    registerInspectorEvents(DOMDomainFrontend);
+
+    const originalChildNodeInserted: (parentId: number, lastId: number, node: string | DOMNode) => void = DOMDomainFrontend.childNodeInserted;
+
+    DOMDomainFrontend.childNodeInserted = (parentId: number, lastId: number, node: DOMNode) => {
+        originalChildNodeInserted(parentId, lastId, JSON.stringify(node.toObject()));
+    }
+}
+
+export function attachDOMInspectorCommandCallbacks(DOMDomainBackend: InspectorCommands) {
+    DOMDomainBackend.getDocument = () => {
+        return JSON.stringify(getDocument());
+    };
+
+    DOMDomainBackend.getComputedStylesForNode = (nodeId) => {
+        return JSON.stringify(getComputedStylesForNode(nodeId));
+    };
+
+    DOMDomainBackend.removeNode = removeNode;
+    DOMDomainBackend.setAttributeAsText = setAttributeAsText;
+}
+
+export function attachCSSInspectorCommandCallbacks(CSSDomainFrontend: InspectorCommands) {
+    // no op
+}