Make a global for embed detection. Don't capture mod-S when embedded

This makes it so save events properly propagate out of the webview and to the
surrounding context. This is a good thing for VScode

Author: jpolitz

src/web/js/beforePyret.js

@@ -1460,15 +1460,18 @@ $(function() {
 
   let initialState = params["get"]["initialState"];
 
+  window.PYRET_IS_EMBEDDED = false;
   if (typeof acquireVsCodeApi === "function") {
     window.MESSAGES = makeEvents({
       CPO: CPO,
       sendPort: acquireVsCodeApi(),
       receivePort: window,
       initialState
     });
+    window.PYRET_IS_EMBEDDED = true;
   }
   else if((window.parent && (window.parent !== window))) {
     window.MESSAGES = makeEvents({ CPO: CPO, sendPort: window.parent, receivePort: window, initialState });
+    window.PYRET_IS_EMBEDDED = true;
   }
 });

src/web/js/cpo-main.js

@@ -666,11 +666,17 @@
 
       // save
       // On Mac mod ends up mapping to command+s whereas on Windows and Linux it maps to ctrl+s.
-      Mousetrap.bindGlobal('mod+s', function(e) {
-        CPO.save();
-        e.stopImmediatePropagation();
-        e.preventDefault();
-      });
+      // Saving has a special condition: when embedded we want the Ctrl-S to
+      // propagate up. We could fire a special “save” event, but for contexts
+      // like VScode it is nice to have the “real” Cmd-S event fire to get
+      // good default behavior
+      if(!PYRET_IS_EMBEDDED) {
+        Mousetrap.bindGlobal('mod+s', function(e) {
+          CPO.save();
+          e.stopImmediatePropagation();
+          e.preventDefault();
+        });
+      }
 
       // resize, Toggle sizing of the editor window between 50% and last resize
       Mousetrap.bindGlobal('ctrl+m', function(e){