Fallback to non worker tfjs when on Safari (#193)

Safari's worker limitations mean that detection threads in the worker barely function. Until Apple quits being whiny jerks about PWAs, this workaround is required to bypass the message calls to the workers and use the old single threaded system when Safari is detected.

Reviewed-on: #193

src/js/store.js

@@ -9,7 +9,8 @@ const state = reactive({
     useExternal: 'optional',
     siteDemo: false,
     externalServerList: [],
-    infoUrl: false
+    infoUrl: false,
+    safariBrowser: false
   })
 
 const set = (config, confObj) => {
@@ -21,6 +22,10 @@ const agree = () => {
   state.disclaimerAgreement = true
 }
 
+const safariDetected = () => {
+  state.safariBrowser = true
+}
+
 const getServerList = () => {
   if (state.useExternal == 'required') {
     return state.externalServerList[0]
@@ -50,8 +55,10 @@ export default () => ({
   getVersion: computed(() => state.version),
   getIconSet: computed(() => state.regionIconSet),
   getInfoUrl: computed(() => state.infoUrl),
+  isSafari: computed(() => state.safariBrowser),
   set,
   agree,
+  safariDetected,
   getServerList,
   toggleFullscreen
 })