fixup! add Profiler.increment and Profiler.frame

src/engine/execute.js

@@ -192,7 +192,7 @@ class BlockCached {
         this.mutation = cached.mutation;
 
         /**
-         * Profiler block is configured with.
+         * The profiler the block is configured with.
          * @type {?Profiler}
          */
         this._profiler = null;
@@ -382,7 +382,13 @@ class BlockCached {
     }
 }
 
-const prepareBlockProfiling = function (profiler, blockCached) {
+/**
+ * Initialize a BlockCached instance so its command/hat
+ * block and reporters can be profiled during execution.
+ * @param {Profiler} profiler - The profiler that is currently enabled.
+ * @param {BlockCached} blockCached - The blockCached instance to profile.
+ */
+const _prepareBlockProfiling = function (profiler, blockCached) {
     blockCached._profiler = profiler;
 
     if (blockFunctionProfilerId === -1) {
@@ -570,6 +576,10 @@ const execute = function (sequencer, thread) {
         if (blockCached._profiler !== runtime.profiler) {
             prepareBlockProfiling(runtime.profiler, blockCached);
         }
+        // Determine the index that is after the last executed block. `i` is
+        // currently the block that was just executed. `i + 1` will be the block
+        // after that. `length` with the min call makes sure we don't try to
+        // reference an operation outside of the set of operations.
         const end = Math.min(i + 1, length);
         for (let p = start; p < end; p++) {
             ops[p]._profilerFrame.count += 1;

src/engine/profiler.js

@@ -132,10 +132,25 @@ class Profiler {
          */
         this.records = [];
 
+        /**
+         * An array of frames incremented on demand instead as part of start
+         * and stop.
+         * @type {Array.<ProfilerFrame>}
+         */
         this.increments = [];
 
+        /**
+         * An array of profiler frames separated by counter argument. Generally
+         * for Scratch these frames are separated by block function opcode.
+         * This tracks each time an opcode is called.
+         * @type {Array.<ProfilerFrame>}
+         */
         this.counters = [];
 
+        /**
+         * A frame with no id or argument.
+         * @type {ProfilerFrame}
+         */
         this.nullFrame = new ProfilerFrame(-1);
 
         /**