Minor refactor in readEmAsmArgs. NFC

Split out from #19980

src/library.js

@@ -2887,19 +2887,17 @@ addToLibrary({
 #endif
       // Floats are always passed as doubles, and doubles and int64s take up 8
       // bytes (two 32-bit slots) in memory, align reads to these:
-      buf += (ch != 105/*i*/) & buf;
+      buf += (ch != {{{ charCode('i') }}}) & buf;
+      readEmAsmArgsArray.push(
+        ch == {{{ charCode('i') }}} ? HEAP32[buf] :
 #if MEMORY64
-      // Special case for pointers under wasm64 which we read as int53 Numbers.
-      if (ch == 112/*p*/) {
-        readEmAsmArgsArray.push(readI53FromI64(buf++ << 2));
-      } else
+        // Special case for pointers under wasm64 which we read as int53 Numbers.
+        ch == {{{ charCode('p') }}} ? {{{ makeGetValue('buf++ << 2', 0, '*') }}} :
 #endif
-      readEmAsmArgsArray.push(
-        ch == 105/*i*/ ? HEAP32[buf] :
 #if WASM_BIGINT
-       (ch == 106/*j*/ ? HEAP64 : HEAPF64)[buf++ >> 1]
+        (ch == {{{ charCode('j') }}} ? HEAP64 : HEAPF64)[buf++ >> 1]
 #else
-       HEAPF64[buf++ >> 1]
+        HEAPF64[buf++ >> 1]
 #endif
       );
       ++buf;

test/test_core.py

@@ -2144,6 +2144,7 @@ def test_inlinejs4(self):
 ''', 'false', assert_returncode=NON_ZERO)
 
   def test_em_asm(self):
+    self.maybe_closure()
     self.do_core_test('test_em_asm.cpp')
 
   def test_em_asm_c(self):