chore: Make field declarations explicit

This used to be valid code:

```
class Foo {
  constructor() {
    this.bar = ‘string’;
  }
}
```

This will now fail since ‘bar’ is not explicitly
defined as a field. We now have to write:

```
class Foo {
  bar:string; // << REQUIRED
  constructor() {
    this.bar = ‘string’;
  }
}
```

tools/transpiler/spec/annotations_spec.js

@@ -6,6 +6,8 @@ class Inject {}
 class Bar {}
 
 class Provide {
+  token;
+
   @CONST()
   constructor(token) {
     this.token = token;
@@ -13,6 +15,8 @@ class Provide {
 }
 
 class AnnotateMe {
+  maybe;
+
   @CONST()
   constructor({maybe = 'default'} = {}) {
     this.maybe = maybe;

tools/transpiler/spec/arrow_functions_spec.js

@@ -13,6 +13,8 @@ var max = (a, b) => {
 };
 
 class LexicalThis {
+  zero;
+
   constructor() {
     this.zero = 0;
   }

tools/transpiler/spec/classes_spec.js

@@ -1,9 +1,10 @@
 import {ddescribe, describe, it, expect} from 'test_lib/test_lib';
 import {CONST} from './fixtures/annotations';
 
-// Constructor
-// Define fields
 class Foo {
+  a;
+  b;
+
   constructor(a, b) {
     this.a = a;
     this.b = b;
@@ -15,6 +16,8 @@ class Foo {
 }
 
 class SubFoo extends Foo {
+  c;
+
   constructor(a, b) {
     this.c = 3;
     super(a, b);
@@ -25,6 +28,8 @@ class SubFoo extends Foo {
 class ConstClass {}
 
 class Const {
+  a;
+
   @CONST
   constructor(a:number) {
     this.a = a;
@@ -32,6 +37,8 @@ class Const {
 }
 
 class SubConst extends Const {
+  b;
+
   @CONST
   constructor(a:number, b:number) {
     super(a);

tools/transpiler/spec/functions_spec.js

@@ -5,6 +5,8 @@ function sum(a, b) {
 }
 
 class ConstructorWithNamedParams {
+  sum;
+
   constructor(a, {b=1, c=2}) {
     this.sum = a + b + c;
   }

tools/transpiler/spec/types_spec.js

@@ -30,6 +30,9 @@ class Bar {
 }
 
 class Foo {
+  a;
+  b;
+
   constructor(a: number, b: number) {
     this.a = a;
     this.b = b;

tools/transpiler/src/codegeneration/ClassTransformer.js

@@ -25,7 +25,6 @@ import {
 } from 'traceur/src/syntax/trees/ParseTrees';
 
 import {
-  ClassFieldDeclaration,
   PropertyConstructorAssignment
 } from '../syntax/trees/ParseTrees';
 
@@ -73,30 +72,6 @@ export class ClassTransformer extends ParseTreeTransformer {
         // Rename "constructor" to the class name.
         elementTree.name.literalToken.value = className;
 
-        // Collect all fields, defined in the constructor.
-        elementTree.body.statements.forEach(function(statement) {
-          var exp = statement.expression;
-          if (exp &&
-              exp.type === BINARY_EXPRESSION &&
-              exp.operator.type === EQUAL &&
-              exp.left.type === MEMBER_EXPRESSION &&
-              exp.left.operand.type === THIS_EXPRESSION) {
-
-            var typeAnnotation;
-
-            if (exp.right.type === IDENTIFIER_EXPRESSION) {
-              // `this.field = variable;`
-              // we can infer the type of the field from the variable when it is a typed arg
-              var varName = exp.right.getStringValue();
-              typeAnnotation = argumentTypesMap[varName] || null;
-            }
-
-            var fieldName = exp.left.memberName.value;
-            var lvalue = new BindingIdentifier(tree.location, fieldName);
-            fields.push(new ClassFieldDeclaration(tree.location, lvalue, typeAnnotation, isConst));
-          }
-        });
-
         // Compute the initializer list
         var initializerList = [];
         var superCall = that._extractSuperCall(elementTree.body);
@@ -149,6 +124,11 @@ export class ClassTransformer extends ParseTreeTransformer {
 
     // Add the field definitions to the beginning of the class.
     tree.elements = fields.concat(tree.elements);
+    if (isConst) {
+      tree.elements.forEach(function(element) {
+        element.isFinal = true;
+      });
+    }
 
     return super.transformClassDeclaration(tree);
   }

tools/transpiler/src/outputgeneration/DartParseTreeWriter.js

@@ -45,8 +45,11 @@ export class DartParseTreeWriter extends JavaScriptParseTreeWriter {
     }
 
     if (tree.typeAnnotation === null) {
-      this.write_(VAR);
+      this.write_(tree.isFinal ? 'final' : VAR);
     } else {
+      if (tree.isFinal) {
+        this.write_('final');
+      }
       this.writeType_(tree.typeAnnotation);
     }
     this.writeSpace_();
@@ -211,6 +214,7 @@ export class DartParseTreeWriter extends JavaScriptParseTreeWriter {
       case 'number': return 'num';
       case 'boolean': return 'bool';
       case 'string': return 'String';
+      case 'any': return 'dynamic';
       case 'Promise': return 'Future';
       default: return typeName;
     }
@@ -244,25 +248,6 @@ export class DartParseTreeWriter extends JavaScriptParseTreeWriter {
     }
   }
 
-  visitClassFieldDeclaration(tree) {
-    if (tree.isFinal) {
-      // `final <type> name;` or `final name;` for untyped variable
-      this.write_('final');
-      this.writeSpace_();
-      this.writeType_(tree.typeAnnotation);
-    } else {
-      // `<type> name;` or `var name;`
-      if (tree.typeAnnotation) {
-        this.writeType_(tree.typeAnnotation);
-      } else {
-        this.write_(VAR);
-        this.writeSpace_();
-      }
-    }
-
-    this.write_(tree.lvalue.getStringValue());
-    this.write_(SEMI_COLON);
-  }
 
   writeType_(typeAnnotation) {
     if (!typeAnnotation) {

tools/transpiler/src/syntax/trees/ParseTrees.js

@@ -4,36 +4,6 @@ import {PropertyMethodAssignment} from 'traceur/src/syntax/trees/ParseTrees';
 
 import * as ParseTreeType from './ParseTreeType';
 
-// Class field declaration
-export class ClassFieldDeclaration extends ParseTree {
-  constructor(location, lvalue, typeAnnotation, isFinal) {
-    this.location = location;
-    this.lvalue = lvalue;
-    this.typeAnnotation = typeAnnotation;
-    this.isFinal = isFinal;
-  }
-
-  get type() {
-    return CLASS_FIELD_DECLARATION;
-  }
-
-  visit(visitor) {
-    if (visitor.visitClassFieldDeclaration) {
-      visitor.visitClassFieldDeclaration(this);
-    }
-  }
-
-  transform(transformer) {
-    if (transformer.transformClassFieldDeclaration) {
-      return transformer.transformClassFieldDeclaration(this);
-    }
-
-    return this;
-  }
-}
-
-var CLASS_FIELD_DECLARATION = ParseTreeType.CLASS_FIELD_DECLARATION;
-
 // Class constructor
 export class PropertyConstructorAssignment extends PropertyMethodAssignment {
   /**