[test] Parse start hex offset when extracting WAT address in test_dwarf (#27455)

WebAssembly/binaryen#8944 changed WAT code
offset annotations from single addresses `;; code offset: 0x8` to
address ranges `;; code offset: 0x8 - 0xa`.

Extracting `.split()[0]` works with both single addresses and address
ranges.

Author: sbc100

test/test_core.py

@@ -8164,7 +8164,7 @@ def get_wat_addr(call_index):
       start_addr_loc = wat.find('0x', call_loc)
       assert start_addr_loc > 0
       start_addr_loc_end = wat.find('\n', start_addr_loc)
-      start_addr = int(wat[start_addr_loc:start_addr_loc_end], 0)
+      start_addr = int(wat[start_addr_loc:start_addr_loc_end].split()[0], 0)
       # the call ends with the drop, which is the last in the stream, at the
       # highest address
       end_addr_loc = wat.rfind('drop', 0, call_loc)
@@ -8173,7 +8173,7 @@ def get_wat_addr(call_index):
       assert end_addr_loc > 0
       end_addr_loc_end = wat.find('\n', end_addr_loc)
       assert end_addr_loc_end > 0
-      end_addr = int(wat[end_addr_loc:end_addr_loc_end], 0)
+      end_addr = int(wat[end_addr_loc:end_addr_loc_end].split()[0], 0)
       return (start_addr, end_addr)
 
     # match up the DWARF and the wat