Handling of star_expr and some async issues.

test/normalizer_issue_files/allowed_syntax_python3.5.py

@@ -8,6 +8,9 @@ async def foo():
     await bar()
     #: E901
     yield from []
+    return
+    #: E901
+    return ''
 
 
 # With decorator it's a different statement.
@@ -17,3 +20,6 @@ async def foo():
     await bar()
     #: E901
     yield from []
+    return
+    #: E901
+    return ''