[JS Legacy] Fix returning Char from suspend functions (KT-44221)

Mark translated expression with a proper type, like we do with
non-suspending calls, to coerce it later.

compiler/testData/codegen/box/coroutines/kt44221.kt

@@ -0,0 +1,24 @@
+// WITH_RUNTIME
+
+import kotlin.coroutines.*
+
+fun launch(block: suspend () -> String): String {
+    var result = ""
+    block.startCoroutine(Continuation(EmptyCoroutineContext) { result = it.getOrThrow() })
+    return result
+}
+
+
+private class CharTest {
+    private val test: Char = '!'
+
+    fun simpleTest() = launch {
+        val ch = get()
+        if (ch == '!') "OK" else "Fail"
+    }
+
+    suspend fun get(): Char? = test
+}
+
+
+fun box(): String = CharTest().simpleTest()