Add special handler for CancellationError in window.onerror.
Add special handler for CancellationError in window.onerror.

vogdb/cm,njam/CM,zazabe/cm,tomaszdurka/CM,vogdb/cm,cargomedia/CM,alexispeter/CM,njam/CM,zazabe/cm,alexispeter/CM,zazabe/cm,fauvel/CM,fauvel/CM,tomaszdurka/CM,alexispeter/CM,fauvel/CM,cargomedia/CM,fauvel/CM,njam/CM,vogdb/cm,vogdb/cm,njam/CM,cargomedia/CM,alexispeter/CM,tomaszdurka/CM,tomaszdurka/CM,cargomedia/CM,njam/CM,zazabe/cm,tomaszdurka/CM,fauvel/CM,vogdb/cm