enh(swift): add async/await keywords (#3048)

* (swift) add async/await keywords
* (swift) add test case for async/await

CHANGES.md

@@ -28,6 +28,7 @@ Language grammar improvements:
 - enh(css) Add `font-smoothing` to attributes list for CSS (#3027) [AndyKIron][]
 - fix(python) Highlight `print` and `exec` as a builtin (#1468) [Samuel Colvin][]
 - fix(csharp) Fix unit being highlighted instead of uint (#3046) [Spacehamster][]
+- enh(swift) add async/await keywords (#3048) [Bradley Mackey][]
 
 Deprecations:
 

src/languages/lib/kws_swift.js

@@ -33,6 +33,8 @@ export const keywords = [
   // will result in additional modes being created to scan for those keywords to
   // avoid conflicts with other rules
   'associatedtype',
+  'async',
+  'await',
   /as\?/, // operator
   /as!/, // operator
   'as', // operator

test/markup/swift/keywords.expect.txt

@@ -15,6 +15,7 @@ x <span class="hljs-keyword">is</span> <span class="hljs-type">String</span>
 <span class="hljs-literal">true</span> <span class="hljs-literal">false</span> <span class="hljs-literal">nil</span>
 <span class="hljs-keyword">fileprivate(set)</span> <span class="hljs-keyword">internal(set)</span> <span class="hljs-keyword">open(set)</span> <span class="hljs-keyword">private(set)</span> <span class="hljs-keyword">public(set)</span>
 <span class="hljs-keyword">unowned(safe)</span> <span class="hljs-keyword">unowned(unsafe)</span>
+<span class="hljs-keyword">async</span> <span class="hljs-keyword">await</span>
 
 <span class="hljs-keyword">#if</span>
 <span class="hljs-keyword">#error</span>(<span class="hljs-string">&quot;Error&quot;</span>)

test/markup/swift/keywords.txt

@@ -15,6 +15,7 @@ try? try! try
 true false nil
 fileprivate(set) internal(set) open(set) private(set) public(set)
 unowned(safe) unowned(unsafe)
+async await
 
 #if
 #error("Error")