Constructors represented "as in Java".

TODO: extract nested initializers somehow.

compiler/testData/ir/irText/classes/initVar.kt

@@ -0,0 +1,38 @@
+class TestInitVarFromParameter(var x: Int)
+
+class TestInitVarInClass {
+    var x = 0
+}
+
+class TestInitVarInInitBlock {
+    var x: Int
+    init {
+        x = 0
+    }
+}
+
+class TestInitVarWithCustomSetter {
+    var x = 0
+        set(value) { field = value }
+}
+
+class TestInitVarWithCustomSetterWithExplicitCtor {
+    var x: Int
+        set(value) { field = value }
+
+    init {
+        x = 0
+    }
+
+    constructor()
+}
+
+class TestInitVarWithCustomSetterInCtor {
+    var x: Int set(value) {
+        field = value
+    }
+
+    constructor() {
+        x = 42
+    }
+}