KT-3457 fix: added missed spread operator and receiver became format template

libraries/stdlib/src/kotlin/StringsJVM.kt

@@ -36,7 +36,7 @@ public inline fun String.toCharArray() : CharArray = (this as java.lang.String).
 
 public inline fun String.toCharList(): List<Char> = toCharArray().toList()
 
-public inline fun String.format(format : String, vararg args : Any?) : String = java.lang.String.format(format, args)
+public inline fun String.format(vararg args : Any?) : String = java.lang.String.format(this, *args)
 
 public inline fun String.split(regex : String) : Array<String> = (this as java.lang.String).split(regex)
 

libraries/stdlib/test/StringJVMTest.kt

@@ -236,4 +236,8 @@ class StringJVMTest {
         assertEquals("", data.take(-7))
         assertEquals(data, data.take(data.length + 42))
     }
+
+    test fun formatter() {
+        assertEquals("12", "%d%d".format(1, 2))
+    }
 }