Fix instruction cycle cost assertion check

my_modules/pcjs-client/lib/cpu.js

@@ -1016,7 +1016,10 @@ CPU.prototype.setBurstCycles = function(nCycles)
         var nDelta = this.nStepCycles - nCycles;
         /*
          * NOTE: If nDelta is negative, we will actually be increasing nStepCycles and nBurstCycles.
+         * Which is OK, but if we're also taking snapshots of the cycle counts, to make sure that instruction
+         * costs are being properly assessed, then we need to update nSnapCycles as well.
          */
+        if (DEBUG) this.nSnapCycles -= nDelta;
         this.nStepCycles -= nDelta;
         this.nBurstCycles -= nDelta;
         return true;