Dev ios wkwebview

[yueyuzhao]

Resolves

upgrade UIWebView to WKWebView

• Resolves Upgrade to WKWebView on iOS #274

Proposed Changes

WKWebView differs from UIWebView very much, we can't get result from the native
codes directly. I introduced Promise for javascript native calling and async/await
to reduce complexity.

nothing needs to be changed for android.

Reason for Changes

• .gitignore package-lock.json is not upload to the codebase and should be ignore.
• package.json @babel/polyfill and babel-preset-stage-3 helps compile async/await to es2015 stage-3
• JsBridge.m, bridging JS messages and implementing WKScriptMessageHandler
• JsRequest.m, wrapping messages that JS sent and return the native result
• View.xib, no UIWebView needed anymore, replace it with a normal View file
• iOS.js, adapting javascript call to native code.

Test Coverage

• display/create/edit/delete projects
• recording/playing sounds
• GUI sounds
• taking pictures
• share project via Airdrop
• share project via Email
• open project via Airdrop
• open project via Email

[chrisgarrity]

@yueyuzhao thank you for the PR. That's a very elegant solution for the didReceiveScriptMessage handler, and the stackoverflow link has such a thorough explanation! Unfortunately, we can't accept this PR as is as it will create conflicts with our work. I decided that it was finally time to refactor the interface layer so that it stopped being 'iOS' everywhere. The PR that refactors the interface is up now. Since we're splitting the iOS and Android interfaces, there's no need to try to maintain the tabletinterface calls with async/await. We're also free to change how iOS.js deals with the WKWebview calls.

[chrisgarrity]

Closing in favor of https://github.com/LLK/scratchjr/pull/291. Thanks @yueyuzhao.