JS: fix translation of augmented assignment when RHS changes value of LHS

compiler/testData/codegen/box/increment/augmentedAssignmentWithComplexRhs.kt

@@ -0,0 +1,23 @@
+// WITH_RUNTIME
+import kotlin.test.*
+
+var log = ""
+var result = 20
+
+fun <T> id(value: T) = value
+
+fun box(): String {
+    result += if (id("true") == "true") {
+        result += 10
+        log += "true chosen"
+        3
+    }
+    else {
+        4
+    }
+
+    assertEquals(23, result)
+    assertEquals("true chosen", log)
+
+    return "OK"
+}