Initial implementation of platformStatic

compiler/testData/codegen/boxWithStdlib/platformStatic/convention.kt

@@ -0,0 +1,31 @@
+class B(var s: Int = 0) {
+
+}
+
+object A {
+
+    fun test1(v: B) {
+        v += B(1000)
+    }
+
+    platformStatic fun B.plusAssign(b: B) {
+        this.s += b.s
+    }
+}
+
+fun box(): String {
+
+    val b1 = B(11)
+
+    with(A) {
+        b1 += B(1000)
+    }
+
+    if (b1.s != 1011) return "fail 1"
+
+    val b = B(11)
+    A.test1(b)
+    if (b.s != 1011) return "fail 2"
+
+    return "OK"
+}