I wonder what they mean by scalable source maps? The last time they proposed an alternative to source maps they basically proposed shipping down an AST structur

I wonder what they mean by scalable source maps? The last time they proposed an alternative to source maps they basically proposed shipping down an AST structure which was even larger. Current source maps already tax the debugger for large programs, so much so that for GWT we had to implement optimizations in the source map generator to avoid generating nodes that are not helpful for debugging but which cause bloat.