Replace deprecated lambda syntax in testData

It's done with similar constructions where possible trying to preserve
intended behavior.
Some usages are removed because they test exactly the feature that
we are going to drop soon.

js/js.translator/testData/expression/function/cases/manglingStability.kt

@@ -124,8 +124,8 @@ public val A.boo: Int
     get() = 1
 public fun A.boo(): Int = 2
 
-val public_ext_f = { A.(): Int -> this.foo() + this.foo }
-val public_ext_b = { A.(): Int -> this.boo() + this.boo }
+val public_ext_f: A.() -> Int = { -> this.foo() + this.foo }
+val public_ext_b: A.() -> Int = { -> this.boo() + this.boo }
 
 interface TestPublicInTrait {
     public fun foo(): Int = 2