Fixed code after merge of 'develop' with TestCoroutineContext

* Moved 'kotlinx-coroutines-test' to a new root folder
* Removed ThreadSafeHead duplication by promoting it core's internal
  class to public @InternalCoroutinesApi

Author: elizarov

core/kotlinx-coroutines-test/src/internal/Synchronized.kt

@@ -4,21 +4,28 @@
 
 package kotlinx.coroutines.internal
 
+import kotlinx.coroutines.*
 import java.util.*
 
-internal interface ThreadSafeHeapNode {
+/**
+ * @suppress **This an internal API and should not be used from general code.**
+ */
+@InternalCoroutinesApi
+public interface ThreadSafeHeapNode {
     public var heap: ThreadSafeHeap<*>?
     public var index: Int
 }
 
 /**
  * Synchronized binary heap.
+ * @suppress **This an internal API and should not be used from general code.**
  */
-internal class ThreadSafeHeap<T> : SynchronizedObject() where T: ThreadSafeHeapNode, T: Comparable<T> {
+@InternalCoroutinesApi
+public class ThreadSafeHeap<T> : SynchronizedObject() where T: ThreadSafeHeapNode, T: Comparable<T> {
     private var a: Array<T?>? = null
 
-    @JvmField @PublishedApi @Volatile
-    internal var size = 0
+    @JvmField @Volatile
+    public var size = 0
 
     public val isEmpty: Boolean get() = size == 0
 

core/kotlinx-coroutines-test/src/internal/ThreadSafeHeap.kt

@@ -1,11 +1,13 @@
+/*
+ * Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
 package kotlinx.coroutines.test
 
 import kotlinx.coroutines.*
-import kotlinx.coroutines.test.internal.ThreadSafeHeap
-import kotlinx.coroutines.test.internal.ThreadSafeHeapNode
-import java.util.concurrent.atomic.AtomicLong
-import kotlin.coroutines.CoroutineContext
-import kotlin.math.max
+import kotlinx.coroutines.internal.*
+import java.util.concurrent.atomic.*
+import kotlin.coroutines.*
 
 /**
  * Control the virtual clock time of a [CoroutineDispatcher].