Reorganize tests and benchmark scripts.

Mainly to get rid of one top level directory. But this will
also be useful when there are tests of the embedding API.

test/language/setter/associativity.wren

@@ -0,0 +1,18 @@
+class Foo {
+  new(value) { _value = value }
+  toString { _value }
+  bar=(value) {
+    _value = value
+    return value
+  }
+}
+
+var a = new Foo("a")
+var b = new Foo("b")
+var c = new Foo("c")
+
+// Assignment is right-associative.
+a.bar = b.bar = c.bar = "d"
+IO.print(a.toString) // expect: d
+IO.print(b.toString) // expect: d
+IO.print(c.toString) // expect: d

test/language/setter/grouping.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar=(value) { value }
+}
+
+var foo = new Foo
+(foo.bar) = "value" // expect error

test/language/setter/infix_operator.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar=(value) { value }
+}
+
+var foo = new Foo
+"a" + foo.bar = "value" // expect error

test/language/setter/instance.wren

@@ -0,0 +1,8 @@
+class Foo {
+  bar=(value) {
+    IO.print(value)
+  }
+}
+
+var foo = new Foo
+foo.bar = "value" // expect: value

test/language/setter/is.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar=(value) { value }
+}
+
+var foo = new Foo
+a is foo.bar = "value" // expect error

test/language/setter/prefix_operator.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar=(value) { value }
+}
+
+var foo = new Foo
+!foo.bar = "value" // expect error

test/language/setter/result.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar=(value) { "result" }
+}
+
+var foo = new Foo
+IO.print(foo.bar = "value") // expect: result

test/language/setter/same_name_as_method.wren

@@ -0,0 +1,8 @@
+class Foo {
+  bar=(value) { IO.print("set") }
+  bar { IO.print("get") }
+}
+
+var foo = new Foo
+foo.bar = "value" // expect: set
+foo.bar // expect: get

test/language/setter/static.wren

@@ -0,0 +1,7 @@
+class Foo {
+  static bar=(value) {
+    IO.print(value)
+  }
+}
+
+Foo.bar = "value" // expect: value