Optimization to reuse BindingContext in completion

idea/idea-completion/testData/incrementalResolve/codeAboveChanged.kt

@@ -0,0 +1,12 @@
+fun foo(p1: Int, p2: String): Int {
+    val v1 = p2<change>
+    val v2 = 123
+    return <before><caret>
+}
+
+// TYPE: ".hashCode()"
+// COMPLETION_TYPE: SMART
+// EXIST: v1
+// EXIST: v2
+// EXIST: p1
+// ABSENT: p2