Don't parse class properties without initializers when classPropertie…

…s is disabled and Flow is enabled (#300)

src/parser/statement.js

@@ -751,8 +751,13 @@ pp.parseClassBody = function (node) {
 };
 
 pp.parseClassProperty = function (node) {
+  const noPluginMsg = "You can only use Class Properties when the 'classProperties' plugin is enabled.";
+  if (!node.typeAnnotation && !this.hasPlugin("classProperties")) {
+    this.raise(node.start, noPluginMsg);
+  }
+
   if (this.match(tt.eq)) {
-    if (!this.hasPlugin("classProperties")) this.unexpected();
+    if (!this.hasPlugin("classProperties")) this.raise(this.state.start, noPluginMsg);
     this.next();
     node.value = this.parseMaybeAssign();
   } else {

test/fixtures/experimental/class-properties/with-initializer-and-type-no-plugin/actual.js

@@ -0,0 +1,3 @@
+class Foo {
+  bar: string = 'bizz';
+}

test/fixtures/experimental/class-properties/with-initializer-and-type-no-plugin/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": ["flow"],
+  "throws": "You can only use Class Properties when the 'classProperties' plugin is enabled. (2:14)"
+}

test/fixtures/experimental/class-properties/with-initializer-missing-plugin/actual.js

@@ -0,0 +1,3 @@
+class Foo {
+  bar = 'bizz';
+}

test/fixtures/experimental/class-properties/with-initializer-missing-plugin/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "You can only use Class Properties when the 'classProperties' plugin is enabled. (2:2)"
+}

test/fixtures/experimental/class-properties/without-initializer-missing-plugin/actual.js

@@ -0,0 +1,3 @@
+class Foo {
+  bar;
+}

test/fixtures/experimental/class-properties/without-initializer-missing-plugin/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "You can only use Class Properties when the 'classProperties' plugin is enabled. (2:2)"
+}