Destroy attached shadow block when input is destroyed.

core/block.js

@@ -1232,8 +1232,15 @@ Blockly.Block.prototype.removeInput = function(name, opt_quiet) {
   for (var i = 0, input; input = this.inputList[i]; i++) {
     if (input.name == name) {
       if (input.connection && input.connection.targetConnection) {
-        // Disconnect any attached block.
-        input.connection.targetBlock().unplug();
+        input.connection.setShadowDom(null);
+        var block = input.connection.targetBlock();
+        if (block.isShadow()) {
+          // Destroy any attached shadow block.
+          block.dispose();
+        } else {
+          // Disconnect any attached normal block.
+          block.unplug();
+        }
       }
       input.dispose();
       this.inputList.splice(i, 1);

core/block_svg.js

@@ -499,7 +499,7 @@ Blockly.BlockSvg.prototype.onMouseDown_ = function(e) {
     // Right-click.
     this.showContextMenu_(e);
   } else if (!this.isMovable()) {
-    // Allow unmovable blocks to be selected and context menued, but not
+    // Allow immovable blocks to be selected and context menued, but not
     // dragged.  Let this event bubble up to document, so the workspace may be
     // dragged instead.
     return;