Chrome devtools elements tab support for Android (#4351)

* Enable chrome-devtools elemets tab

* Trigger updates when property is chaned form native

* Tslint fixes

* Don't run dom-elemet tests in IOS

* fix tests

* Create package.json

* Update package.json

* domNode changed to field for performance

tns-core-modules/debugger/css-agent.ts

@@ -0,0 +1,81 @@
+/*
+    On element select in the inspector the following are requested:
+        - Inline styles -> CSSStyle
+        - Attributes styles -> CSSStyle (Appears as 'Stacklayout[Attributes style]` - unsure of its purpose) irrelevant?
+        - Style matches -> RuleMatch[]
+        - Inherited styles -> InheritedStyleEntry[]
+        - Pseudo Element matches -> PseudoElementMatches[]
+        - Computed Styles for node -> CSSComputedStyleProperty[]
+        - Element Fonts -> PlatformFontUsage
+*/
+
+export interface CSSProperty {
+    name: string
+    value: string
+    disabled: boolean // strikes out the disabled property 
+}
+
+export interface ShorthandEntry { // seems irrelevant - feel free to leave empty for now
+    name: string
+    value: string
+}
+
+export interface CSSStyle {
+    cssProperties: CSSProperty[]
+    shorthandEntries: ShorthandEntry[] // doesn't seem to display anywhere
+    cssText?: string
+}
+
+export interface Value {
+    text: string
+}
+
+export interface SelectorList { // e.g. [".btn", "Button", "Label"]
+    selectors: Value[]
+    text: string // doesn't seem to display anywhere
+}
+
+export interface CSSRule {
+    selectorList: SelectorList
+    origin: string // a constant - "regular"
+    style: CSSStyle
+    styleSheetId?: string // associated stylesheet
+}
+
+export interface RuleMatch {
+    rule: CSSRule
+    matchingSelectors: number[] // index-based - the index of the selector that the node currently inspected matches
+}
+
+export interface InheritedStyleEntry {
+    matchedCSSRules: RuleMatch[]
+    inlineStyle?: CSSStyle
+}
+
+export interface CSSComputedStyleProperty {
+    name: string
+    value: string
+}
+
+export interface PlatformFontUsage {
+    familyName: string
+    glyphCount: number // number of characters in text of element
+    isCustomFont: boolean
+}
+
+export interface CSSStyleSheetHeader {
+    styleSheetId: string // a unique identifier - file name/path should do
+    frameId: string // constant
+    sourceUrl: string
+    origin: string // constant
+    title: string // the same as the id?
+    disabled: boolean // false - if the css has been invalidated/disabled
+    isInLine: boolean // false
+    startLine: number // constant - 1
+    startColumn: number // constant - 1
+}
+
+export interface PseudoElementMatches {
+    pseudoType: string // e.g. last-child
+    matches: RuleMatch[]
+}