Remove filtering of empty lines from grid

I'm not sure what problem this originally solved, but now it makes no
sense.

starfish.js

@@ -109,7 +109,7 @@ class CodeBox {
         this.outputDOM.value = "";
 
         const cbRaw = this.codeBoxDOM.value;
-        const rows = cbRaw.split("\n").filter((r) => r.length);
+        const rows = cbRaw.split("\n");
 
         let maxRowLength = 0;
         for(const row of rows) {