Remove WASM_ASYNC_COMPILATION from the few test cases

We should prefer async compilation in all tests except those that
sepcificially test this option.

tests/interop/test_add_function_post.js

diff --git a/tests/interop/test_add_function_post.js b/tests/interop/test_add_function_post.js
deleted file mode 100644
index c214af8..0000000
--- a/tests/interop/test_add_function_post.js
+++ /dev/null
@@ -1,4 +0,0 @@
-var newFuncPtr = addFunction(function(num) {
-    out('Hello ' + num + ' from JS!');
-}, 'vi');
-Module['callMain']([newFuncPtr.toString()]);

tests/interop/test_add_function_pre.js

diff --git a/tests/interop/test_add_function_pre.js b/tests/interop/test_add_function_pre.js
new file mode 100644
index 0000000..cbdf379
--- /dev/null
+++ b/tests/interop/test_add_function_pre.js
@@ -0,0 +1,8 @@
+Module['postRun'] = function() {
+  console.log("postRun");
+  var newFuncPtr = addFunction(function(num) {
+      out('Hello ' + num + ' from JS!');
+  }, 'vi');
+
+  Module['callMain']([newFuncPtr.toString()]);
+};

tests/test_core.py

diff --git a/tests/test_core.py b/tests/test_core.py
index f1a1a63..9d12109 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -6213,11 +6213,10 @@
 
   ### Integration tests
 
-  @sync
   def test_ccall(self):
     self.emcc_args.append('-Wno-return-stack-address')
     self.set_setting('EXTRA_EXPORTED_RUNTIME_METHODS', ['ccall', 'cwrap'])
-    create_test_file('post.js', '''
+    self.add_pre_run('''
       out('*');
       var ret;
       ret = Module['ccall']('get_int', 'number'); out([typeof ret, ret].join(','));
@@ -6249,7 +6248,6 @@
       out('stack is ok.');
       ccall('call_ccall_again', null);
       ''')
-    self.emcc_args += ['--post-js', 'post.js']
 
     self.set_setting('EXPORTED_FUNCTIONS', ['_get_int', '_get_float', '_get_bool', '_get_string', '_print_int', '_print_float', '_print_bool', '_print_string', '_multi', '_pointer', '_call_ccall_again', '_malloc'])
     self.do_run_in_out_file_test('tests', 'core', 'test_ccall.cpp')
@@ -6434,14 +6432,12 @@
     self.do_run(src, 'waka 4999!')
     self.assertContained('_exported_func_from_response_file_1', open('src.js').read())
 
-  @sync
   def test_add_function(self):
     self.set_setting('INVOKE_RUN', 0)
     self.set_setting('RESERVED_FUNCTION_POINTERS')
     self.set_setting('EXPORTED_RUNTIME_METHODS', ['callMain'])
     src = path_from_root('tests', 'interop', 'test_add_function.cpp')
-    post_js = path_from_root('tests', 'interop', 'test_add_function_post.js')
-    self.emcc_args += ['--post-js', post_js]
+    self.emcc_args += ['--pre-js', path_from_root('tests', 'interop', 'test_add_function_pre.js')]
 
     print('basics')
     self.do_run_in_out_file_test('tests', 'interop', 'test_add_function.cpp')
@@ -7650,7 +7646,7 @@
 |IDBFS is no longer included by default; build with -lidbfs.js|'''
     self.do_run('int main() { return 0; }', expected)
 
-  @sync
+  @no_wasm_backend("https://github.com/emscripten-core/emscripten/issues/9039")
   def test_stack_overflow_check(self):
     self.set_setting('TOTAL_STACK', 1048576)
     self.set_setting('STACK_OVERFLOW_CHECK', 2)