getSymbolResolution: fallback to asset's symbol with non-static dependencies

[mischnic]

Previously, getSymbolResultion would return null in a situation like this (can be caused by importing bufferand also using the global or using __filename while also importing path manually).

Now, it will fallback to the symbol that the asset declares (asset.symbols.get("foo")), which will work fine if the asset doesn't reexport said symbol. If if that symbol was reexported (and has the value $id1$export$id2) then there will definitely have been a dependency with symbols and the corresponding mapping.

This doesn't trigger the Asset was skipped or not found. assertion in the general case because many instances of getSymbolResolution returning null to fallback are handled gracefully (by falling back...). But when building a library, the symbols of the entry have to be determined.

This whole duplicate dependency and missing symbols problem isn't ideal, but this could also occur with two unrelated dependencies. I couldn't think of a reproduction outside of the buffer/path globals.