Remove superfluous AtomicInt value read after write

The new value is already available locally and can be returned directly.

Author: JakeWharton

Diff for: stately-concurrency/src/jsWasmMain/kotlin/co/touchlab/stately/concurrency/AtomicInt.kt

@@ -23,8 +23,9 @@ actual class AtomicInt actual constructor(initialValue: Int) {
     private var internalValue: Int = initialValue
 
     actual fun addAndGet(delta: Int): Int {
-        internalValue += delta
-        return internalValue
+        return (internalValue + delta).also {
+            internalValue = it
+        }
     }
 
     actual fun compareAndSet(expected: Int, new: Int): Boolean {