[JS BE] Make sourceMap generation more precise

- Don't produce mapping for closing bracket in case of expressionBody
 - Map Kt*Function declaration into corresponding js fun declaration
 - Update test data & add new test

js/js.translator/testData/lineNumbers/delegateMemberVal.kt

@@ -13,4 +13,4 @@ class Delegate(val f: () -> Int) {
     }
 }
 
-// LINES: 1 2 3 * 2 2 3 3 3 * 8 7 7 10 10 13 12 12
+// LINES: 1 2 3 * 2 2 3 3 3 3 * 6 8 7 7 10 10 11 13 12 12