getSymbolSize was recently added to WasmObjectFile and has correct sizes
for most symbol types. This makes llvm-symbolizer correctly symbolize
addresses in the middle of the symbol.
When reworking the test I also noticed that the DWARF info seems to be
wrong for the first instruction in each function. I noted that in the test
comments but didn't attempt to fix here.
The only thing missing for basic llvm-symbolizer support is the ability on
lib/Object to get a wasm symbol's section ID, which allows sorting and
computation of the symbols' sizes.
Also, when the WasmAsmParser switches sections on new functions, also add the
section to the list of Dwarf sections if Dwarf is being generated for assembly;
this allows writing of simple tests.
Reviewers: sbc100, jhenderson, aardappel
Differential Revision: https://reviews.llvm.org/D73246
