Cherry-picks from native-mt branch to reduce maintenance burden (Kotlin#2204)

* Immediate dispatcher on JS, test added
* Style fixes

Author: qwwdfsad

buildSrc/src/main/kotlin/Idea.kt

@@ -1,4 +1,5 @@
 object Idea {
+    @JvmStatic // for Gradle
     val active: Boolean
         get() = System.getProperty("idea.active") == "true"
 }

kotlinx-coroutines-core/js/src/Dispatchers.kt

@@ -7,24 +7,19 @@ package kotlinx.coroutines
 import kotlin.coroutines.*
 
 public actual object Dispatchers {
-
     public actual val Default: CoroutineDispatcher = createDefaultDispatcher()
-
-    public actual val Main: MainCoroutineDispatcher = JsMainDispatcher(Default)
-
+    public actual val Main: MainCoroutineDispatcher = JsMainDispatcher(Default, false)
     public actual val Unconfined: CoroutineDispatcher = kotlinx.coroutines.Unconfined
 }
 
-private class JsMainDispatcher(val delegate: CoroutineDispatcher) : MainCoroutineDispatcher() {
-
-    override val immediate: MainCoroutineDispatcher
-        get() = throw UnsupportedOperationException("Immediate dispatching is not supported on JS")
-
+private class JsMainDispatcher(
+    val delegate: CoroutineDispatcher,
+    private val invokeImmediately: Boolean
+) : MainCoroutineDispatcher() {
+    override val immediate: MainCoroutineDispatcher =
+        if (invokeImmediately) this else JsMainDispatcher(delegate, true)
+    override fun isDispatchNeeded(context: CoroutineContext): Boolean = !invokeImmediately
     override fun dispatch(context: CoroutineContext, block: Runnable) = delegate.dispatch(context, block)
-
-    override fun isDispatchNeeded(context: CoroutineContext): Boolean = delegate.isDispatchNeeded(context)
-
     override fun dispatchYield(context: CoroutineContext, block: Runnable) = delegate.dispatchYield(context, block)
-
     override fun toString(): String = toStringInternalImpl() ?: delegate.toString()
 }

kotlinx-coroutines-core/js/test/ImmediateDispatcherTest.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.coroutines
+
+import kotlin.test.*
+
+class ImmediateDispatcherTest : TestBase() {
+
+    @Test
+    fun testImmediate() = runTest {
+        expect(1)
+        val job = launch { expect(3) }
+        withContext(Dispatchers.Main.immediate) {
+            expect(2)
+        }
+        job.join()
+        finish(4)
+    }
+
+    @Test
+    fun testMain() = runTest {
+        expect(1)
+        val job = launch { expect(2) }
+        withContext(Dispatchers.Main) {
+            expect(3)
+        }
+        job.join()
+        finish(4)
+    }
+}

kotlinx-coroutines-core/jvm/src/Executors.kt

@@ -14,7 +14,7 @@ import kotlin.coroutines.*
  * Instances of [ExecutorCoroutineDispatcher] should be closed by the owner of the dispatcher.
  *
  * This class is generally used as a bridge between coroutine-based API and
- * asynchronous API which requires instance of the [Executor].
+ * asynchronous API that requires an instance of the [Executor].
  */
 public abstract class ExecutorCoroutineDispatcher: CoroutineDispatcher(), Closeable {
     /** @suppress */

kotlinx-coroutines-core/native/src/Dispatchers.kt

@@ -7,24 +7,16 @@ package kotlinx.coroutines
 import kotlin.coroutines.*
 
 public actual object Dispatchers {
-
     public actual val Default: CoroutineDispatcher = createDefaultDispatcher()
-
     public actual val Main: MainCoroutineDispatcher = NativeMainDispatcher(Default)
-
     public actual val Unconfined: CoroutineDispatcher get() = kotlinx.coroutines.Unconfined // Avoid freezing
 }
 
 private class NativeMainDispatcher(val delegate: CoroutineDispatcher) : MainCoroutineDispatcher() {
-
     override val immediate: MainCoroutineDispatcher
         get() = throw UnsupportedOperationException("Immediate dispatching is not supported on Native")
-
     override fun dispatch(context: CoroutineContext, block: Runnable) = delegate.dispatch(context, block)
-
     override fun isDispatchNeeded(context: CoroutineContext): Boolean = delegate.isDispatchNeeded(context)
-
     override fun dispatchYield(context: CoroutineContext, block: Runnable) = delegate.dispatchYield(context, block)
-
     override fun toString(): String = toStringInternalImpl() ?: delegate.toString()
 }

ui/kotlinx-coroutines-android/build.gradle.kts

@@ -6,10 +6,6 @@ import org.jetbrains.dokka.DokkaConfiguration.ExternalDocumentationLink
 import org.jetbrains.dokka.gradle.DokkaTask
 import java.net.URL
 
-repositories {
-    google()
-}
-
 configurations {
     create("r8")
 }