StdLib Generators: fix type projections, do not use concat.

libraries/tools/kotlin-stdlib-gen/src/templates/engine/DocExtensions.kt

@@ -32,6 +32,6 @@ object DocExtensions {
         else -> this + "s"
     }
 
-    fun String.prefixWithArticle() = (if ("aeiou".any { this.startsWith(it, ignoreCase = true) }) "an " else "a ").concat(this)
+    fun String.prefixWithArticle() = (if ("aeiou".any { this.startsWith(it, ignoreCase = true) }) "an " else "a ") + this
 
 }

libraries/tools/kotlin-stdlib-gen/src/templates/engine/Engine.kt

@@ -325,7 +325,7 @@ class GenericFunction(val signature: String, val keyword: String = "fun") {
                     .drop(1)
                     .takeWhile { it != '>' }
                     .split(",")
-                    .map { it.removePrefix("out").removePrefix("in").trim() }
+                    .map { it.trim().removePrefix("out").removePrefix("in").trim() }
 
             // TODO: Model for type parameter
             val types = ArrayList(typeParams)