Use "construct" instead of "this" to define constructors.

test/language/constructor/cannot_be_static.wren

@@ -1,4 +1,4 @@
 class Foo {
-  static this new() {} // expect error
-  this static new() {} // expect error
+  static construct new() {} // expect error
+  construct static new() {} // expect error
 }

test/language/constructor/cannot_call_initializer.wren

@@ -1,5 +1,5 @@
 class Foo {
-  this new() {
+  construct new() {
     IO.print("ok")
   }
 }

test/language/constructor/default_calls_new.wren

@@ -1,5 +1,5 @@
 class Foo {
-  this new() {
+  construct new() {
     IO.print("Foo.new()")
   }
 }

test/language/constructor/infix_class_expression.wren

@@ -1,9 +0,0 @@
-class Foo {
-  +(other) { "Foo " + other }
-}
-
-IO.print(Foo.new() + "value") // expect: Foo value
-
-// TODO: Other expressions following a constructor, like new Foo.bar("arg").
-// TODO: Delete this test?
-// TODO: Other constructor tests, like named constructors, etc.

test/language/constructor/named.wren

@@ -1,8 +1,6 @@
-// TODO: Change this.
-
 class Foo {
-  this named() { _field = "named" }
-  this other() { _field = "other" }
+  construct named() { _field = "named" }
+  construct other() { _field = "other" }
 
   toString { _field }
 }

test/language/constructor/no_default.wren

@@ -1,5 +1,5 @@
 class Foo {
-  this real() {}
+  construct real() {}
 }
 
 // Classes do not get an argument-less "new()" if they define a constructor.

test/language/constructor/not_inherited.wren

@@ -1,5 +1,5 @@
 class Foo {
-  this base() {}
+  construct base() {}
 }
 
 class Bar is Foo {}

test/language/constructor/object.wren

@@ -2,12 +2,10 @@
 // super() call in a subclass, so this does that.
 
 class Foo {
-  this new() {
+  construct new() {
     super() // Should not cause a no method error.
     IO.print("ok")
   }
 }
 
 Foo.new() // expect: ok
-
-// TODO: Test that can't invoke initializer on existing instance.

test/language/constructor/super_must_have_args.wren

@@ -1,7 +1,7 @@
 class A {}
 
 class B is A {
-  this new() {
+  construct new() {
     super // expect error
   }
 }

test/language/constructor/superclass.wren

@@ -1,5 +1,5 @@
 class A {
-  this new(arg) {
+  construct new(arg) {
     IO.print("new A ", arg)
     _field = arg
   }
@@ -8,7 +8,7 @@ class A {
 }
 
 class B is A {
-  this new(arg1, arg2) {
+  construct new(arg1, arg2) {
     super(arg2)
     IO.print("new B ", arg1)
     _field = arg1
@@ -18,7 +18,7 @@ class B is A {
 }
 
 class C is B {
-  this new() {
+  construct new() {
     super("one", "two")
     IO.print("new C")
     _field = "c"