Fix creation of uneditable blocks.  Issue #324.
Fix creation of uneditable blocks.  Issue #324.

aravart/speech-blocks,RealTimeWeb/blockly,gengshenghong/scratch-blocks,rachel-fenichel/blockly,jstnhuang/blockly,trinketapp/blockly,trodi/blockly,trinketapp/blockly,mark-friedman/blockly,jstnhuang/blockly,mark-friedman/blockly,nickmain/blockly,mark-friedman/blockly,trodi/blockly,sclements/scratch-blocks,carlosperate/blockly,google/blockly,sclements/scratch-blocks,twodee/blockly,picklesrus/blockly,markocelan/blockly-minecraft,LLK/scratch-blocks,twodee/blockly,markocelan/blockly-minecraft,google/blockly-devtools,lzairdking/blockly,griffpatch/scratch-blocks,google/blockly,groklearning/blockly,dhalupa/blockly,jano42/blockly,joshlory/blockly,twodee/blockly,lzairdking/blockly,google/blockly,markocelan/blockly-minecraft,trodi/blockly,carlosperate/blockly,sclements/scratch-blocks,joshlory/blockly,twodee/blockly,trinketapp/blockly,mark-friedman/blockly,trinketapp/blockly,google/blockly,RealTimeWeb/blockly,dhalupa/blockly,jano42/blockly,LLK/scratch-blocks,google/blockly,TechplexEngineer/blockly,InspectorWidget/blockly,TechplexEngineer/blockly,gengshenghong/scratch-blocks,google/blockly,rachel-fenichel/blockly,aravart/speech-blocks,mark-friedman/blockly,dhalupa/blockly,daarond/blockly,gengshenghong/scratch-blocks,markocelan/blockly-minecraft,groklearning/blockly,griffpatch/scratch-blocks,InspectorWidget/blockly,picklesrus/blockly,InspectorWidget/blockly,rachel-fenichel/blockly,carlosperate/blockly,sclements/scratch-blocks,daarond/blockly,rachel-fenichel/blockly,nickmain/blockly,griffpatch/scratch-blocks,lzairdking/blockly,nickmain/blockly,LLK/scratch-blocks,groklearning/blockly,joshlory/blockly,jstnhuang/blockly,lzairdking/blockly,rachel-fenichel/blockly,google/blockly,griffpatch/scratch-blocks,daarond/blockly,LLK/scratch-blocks,nickmain/blockly,gengshenghong/scratch-blocks,nickmain/blockly,jano42/blockly,sclements/scratch-blocks,griffpatch/scratch-blocks,jstnhuang/blockly,rachel-fenichel/blockly,google/blockly-devtools,gengshenghong/scratch-blocks,twodee/blockly,rachel-fenichel/blockly,LLK/scratch-blocks,nickmain/blockly,hkoi/blockly,carlosperate/blockly,hkoi/blockly,jano42/blockly,trodi/blockly,mark-friedman/blockly,RealTimeWeb/blockly,hkoi/blockly,picklesrus/blockly,twodee/blockly,groklearning/blockly