Patch for emcc to enable source maps for wasm

sm_emcc.patch

diff --git a/emcc.py b/emcc.py
index fdbefe008..54d989c16 100755
--- a/emcc.py
+++ b/emcc.py
@@ -145,6 +145,7 @@ class EmccOptions(object):
     self.exclude_files = []
     self.ignore_dynamic_linking = False
     self.shell_path = shared.path_from_root('src', 'shell.html')
+    self.source_map_base = None
     self.js_libraries = []
     self.bind = False
     self.emrun = False
@@ -1771,7 +1772,7 @@ There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR P
       if shared.Settings.CYBERDWARF:
           execute([shared.PYTHON, shared.path_from_root('tools', 'emdebug_cd_merger.py'), target + '.cd', target+'.symbols'])
 
-      if options.debug_level >= 4:
+      if options.debug_level >= 4 and not shared.Settings.BINARYEN:
         emit_source_maps(target, optimizer.js_transform_tempfiles)
 
       # track files that will need native eols
@@ -1956,6 +1957,11 @@ def parse_args(newargs):
       options.shell_path = newargs[i+1]
       newargs[i] = ''
       newargs[i+1] = ''
+    elif newargs[i].startswith('--source-map-base'):
+      check_bad_eq(newargs[i])
+      options.source_map_base = newargs[i+1]
+      newargs[i] = ''
+      newargs[i+1] = ''
     elif newargs[i].startswith('--js-library'):
       check_bad_eq(newargs[i])
       options.js_libraries.append(newargs[i+1])
@@ -2243,6 +2249,9 @@ def do_binaryen(final, target, asm_target, options, memfile, wasm_binary_target,
     # emit text (at least until wasm gains support for debug info in binaries)
     target_binary = options.debug_level < 3
     if target_binary:
+      cmd += ['--source-map=' + wasm_binary_target + '.map']
+      if options.source_map_base:
+        cmd += ['--source-map-url=' + options.source_map_base + wasm_binary_target + '.map']
       cmd += ['-o', wasm_binary_target]
     else:
       cmd += ['-o', wasm_text_target, '-S']
@@ -2254,6 +2263,9 @@ def do_binaryen(final, target, asm_target, options, memfile, wasm_binary_target,
     if not target_binary:
       cmd = [os.path.join(binaryen_bin, 'wasm-as'), wasm_text_target, '-o', wasm_binary_target]
       if options.debug_level >= 2 or options.profiling_funcs:
+        cmd += ['--source-map=' + wasm_binary_target + '.map']
+        if options.source_map_base:
+          cmd += ['--source-map-url=' + options.source_map_base + wasm_binary_target + '.map']
         cmd += ['-g']
       logging.debug('wasm-as (text => binary): ' + ' '.join(cmd))
       subprocess.check_call(cmd)