KT-4914 Smart completion should work after 'as' and 'as?'

#KT-4914 Fixed

idea/testData/completion/smart/AfterAs.kt

@@ -0,0 +1,11 @@
+fun foo(s: String?){}
+
+fun foo(i: Int){}
+
+fun bar(o: Any) {
+    foo(o as <caret>)
+}
+
+// NUMBER: 2
+// EXIST: String
+// EXIST: Int

idea/testData/completion/smart/AfterAs2.kt

@@ -0,0 +1,11 @@
+fun foo(s: List<String>){}
+
+fun foo(i: Map<String, Int>){}
+
+fun bar(o: Any) {
+    foo(o as <caret>)
+}
+
+// NUMBER: 2
+// EXIST: { lookupString:"List", itemText:"List<String>" }
+// EXIST: { lookupString:"Map", itemText:"Map<String, Int>" }

idea/testData/completion/smart/AfterAs3.kt

@@ -0,0 +1,12 @@
+fun foo(l: List<String>){}
+fun foo(l: List<String>, p: Int){}
+
+fun foo(s: String?){}
+
+fun bar(o: Any) {
+    foo(o as <caret>)
+}
+
+// NUMBER: 2
+// EXIST: { lookupString:"List", itemText:"List<String>" }
+// EXIST: { lookupString:"String", itemText:"String" }