Better glows (#152)

* Strip out old script glowing in thread management

* Add new tracking mechanism for glowing scripts

* Track parents and use them to determine script glows

* Use top-block for a thread if there's nothing on the stack

* Remove `console.log`

src/engine/execute.js

@@ -41,6 +41,7 @@ var execute = function (sequencer, thread) {
         }
         // Skip through the block.
         // (either hat with no predicate, or missing op).
+        thread.requestScriptGlowInFrame = true;
         return;
     }
 
@@ -110,6 +111,12 @@ var execute = function (sequencer, thread) {
         }
     });
 
+    if (typeof primitiveReportedValue === 'undefined') {
+        // No value reported - potentially a command block.
+        // Edge-activated hats don't request a glow; all commands do.
+        thread.requestScriptGlowInFrame = true;
+    }
+
     /**
      * Handle any reported value from the primitive, either directly returned
      * or after a promise resolves.