JS: support int overflow behaviour in augmented assignment

js/js.translator/testData/box/number/assignmentIntOverflow.kt

@@ -0,0 +1,25 @@
+package foo
+
+fun bigValue() = 0x7FFFFFFC
+
+fun mediumValue() = 0x12345
+
+fun box(): String {
+    var v = bigValue()
+    v += 1
+    if (v != 0x7FFFFFFD) return "fail1: $v"
+
+    v = bigValue()
+    v += 8
+    if (v != -0x7FFFFFFC) return "fail2: $v"
+
+    v = mediumValue()
+    v *= 0x23456
+    if (v != -2112496338) return "fail3: $v"
+
+    v = bigValue()
+    v *= bigValue()
+    if (v != 16) return "fail4: $v"
+
+    return "OK"
+}