Change logic compare block to eject mismatched blocks.

blocks/logic.js

@@ -312,15 +312,18 @@ Blockly.Blocks['logic_compare'] = {
     }
     var blockA = this.getInputTargetBlock('A');
     var blockB = this.getInputTargetBlock('B');
-    if (blockA) {
-      this.getInput('B').setCheck(blockA.outputConnection.check_);
-    }
-    if (blockB) {
-      this.getInput('A').setCheck(blockB.outputConnection.check_);
-    }
-    if (!blockA && !blockB) {
-      this.getInput('A').setCheck(null);
-      this.getInput('B').setCheck(null);
+    // Keep track of which block was added second
+    // (so the first block may be ejected upon mismatch).
+    if (blockA && !blockB) {
+      this.blockAPriority_ = false;
+    } else if (!blockA && blockB) {
+      this.blockAPriority_ = true;
+    } else if (blockA && blockB &&
+        !blockA.outputConnection.checkType_(blockB.outputConnection)) {
+      // Mismatch between two inputs.  Disconnect one and bump it away.
+      var child = this.blockAPriority_ ? blockB : blockA;
+      child.setParent(null);
+      child.bumpNeighbours_();
     }
   }
 };