[Wasm] Support coroutines

- Reuse JS IR Suspend function lowering
  - Fix types
  - Disable reinterpretCast-based optimization for inline
    classes
- Add basic support to Wasm stdlib
- Explicitly transform suspend functions into regular functions
  with continuations
- Clean suspend function handling from JS IR codegen

libraries/stdlib/wasm/internal/kotlin/wasm/internal/Coroutines.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("RedundantSuspendModifier")
+
+package kotlin.wasm.internal
+
+import kotlin.coroutines.*
+
+@PublishedApi
+@ExcludedFromCodegen
+internal fun <T> getContinuation(): Continuation<T> =
+    implementedAsIntrinsic
+
+@PublishedApi
+@Suppress("UNCHECKED_CAST")
+internal suspend fun <T> returnIfSuspended(@Suppress("UNUSED_PARAMETER") argument: Any?): T =
+    argument as T
+
+@PublishedApi
+internal fun <T> interceptContinuationIfNeeded(
+    context: CoroutineContext,
+    continuation: Continuation<T>
+) = context[ContinuationInterceptor]?.interceptContinuation(continuation) ?: continuation
+
+
+@PublishedApi
+internal suspend fun getCoroutineContext(): CoroutineContext = getContinuation<Any?>().context
+
+@PublishedApi
+internal suspend fun <T> suspendCoroutineUninterceptedOrReturn(block: (Continuation<T>) -> Any?): T =
+    returnIfSuspended<T>(block(getContinuation<T>()))
+
+@ExcludedFromCodegen
+@PublishedApi
+internal fun <T> startCoroutineUninterceptedOrReturnIntrinsic0(
+    f: (suspend () -> T),
+    completion: Continuation<T>
+): Any? {
+    implementedAsIntrinsic
+}
+
+@ExcludedFromCodegen
+@PublishedApi
+internal fun <R, T> startCoroutineUninterceptedOrReturnIntrinsic1(
+    f: (suspend R.() -> T),
+    receiver: R,
+    completion: Continuation<T>
+): Any? {
+    implementedAsIntrinsic
+}
+
+@ExcludedFromCodegen
+@PublishedApi
+internal fun <R, P, T> startCoroutineUninterceptedOrReturnIntrinsic2(
+    f: (suspend R.(P) -> T),
+    receiver: R,
+    param: P,
+    completion: Continuation<T>
+): Any? {
+    implementedAsIntrinsic
+}