Fix IntArrayList deprecation warning in JvmDependenciesIndexImpl

Copy relevant parts of deprecated IntelliJ's IntArrayList to a new util
class. Also fix some minor IDE inspections.

compiler/util/src/org/jetbrains/kotlin/utils/IntArrayList.kt

@@ -0,0 +1,38 @@
+/*
+ * 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.
+ */
+
+package org.jetbrains.kotlin.utils
+
+// Based on com.intellij.util.containers.IntArrayList.
+class IntArrayList(initialCapacity: Int) {
+    private var data = IntArray(initialCapacity)
+    private var size = 0
+
+    fun trimToSize() {
+        if (size < data.size) {
+            data = data.copyOf(size)
+        }
+    }
+
+    private fun ensureCapacity(minCapacity: Int) {
+        if (minCapacity > data.size) {
+            data = data.copyOf(maxOf(data.size * 3 / 2 + 1, minCapacity))
+        }
+    }
+
+    fun size(): Int = size
+
+    val isEmpty: Boolean get() = size == 0
+
+    operator fun get(index: Int): Int = data[index]
+
+    fun add(o: Int) {
+        ensureCapacity(size + 1)
+        data[size++] = o
+    }
+
+    override fun toString(): String =
+        (0 until size).joinToString(", ", "[", "]") { this[it].toString() }
+}