fix(compiler): Support camelCase property bindings

Fixes #1460

Author: jbdeboer

lib/core_dom/element_binder.dart

@@ -308,6 +308,7 @@ class ElementBinder {
     var jsNode;
     List bindAssignableProps = [];
     bindAttrs.forEach((String prop, AST ast) {
+      prop = camelCase(prop);
       if (jsNode == null) jsNode = new js.JsObject.fromBrowserObject(node);
       scope.watchAST(ast, (v, _) {
         jsNode[prop] = v;

lib/core_dom/selector.dart

@@ -57,6 +57,7 @@ class DirectiveSelector {
     });
   }
 
+
   /**
    * [matchElement] returns an [ElementBinder] or a [TemplateElementBinder] configured with all the
    * directives triggered by the `node`.

lib/utils.dart

@@ -81,6 +81,12 @@ relaxFnArgs(Function fn) {
 
 capitalize(String s) => s.substring(0, 1).toUpperCase() + s.substring(1);
 
+String camelCase(String s) {
+  var part = s.split('-').map((s) => s.toLowerCase());
+  if (part.length <= 1)
+    return part.join();
+  return part.first + part.skip(1).map(capitalize).join();
+}
 
 /// Returns whether or not the given identifier is a reserved word in Dart.
 bool isReservedWord(String identifier) => RESERVED_WORDS.contains(identifier);

test/core_dom/web_components_spec.dart

@@ -71,9 +71,16 @@ main() {
 
     it('should bind to a non-existent property', () {
       registerElement('tests-empty', {});
-      compileAndUpgrade('<tests-empty bind-new-prop=27></tests-empty>');
+      compileAndUpgrade('<tests-empty bind-newprop=27></tests-empty>');
       _.rootScope.apply();
-      expect(customProp('new-prop')).toEqual(27);
+      expect(customProp('newprop')).toEqual(27);
+    });
+
+    it('should bind to a camelCase property', () {
+      registerElement('tests-camel', {});
+      compileAndUpgrade('<tests-camel bind-new-prop=27></tests-camel>');
+      _.rootScope.apply();
+      expect(customProp('newProp')).toEqual(27);
     });
 
     it('should bind to both directives and properties', () {

test/utils_spec.dart

@@ -31,5 +31,19 @@ main() {
       }).toThrowWith(message: 'Unknown function type, expecting 0 to 5 args.');
     });
   });
+
+  describe('camelCase', () {
+    it('should ignore non camelCase', () {
+      expect(camelCase('regular')).toEqual('regular');
+    });
+
+    it('should convert snake-case', () {
+      expect(camelCase('snake-case')).toEqual('snakeCase');
+    });
+
+    it('should lowercase strings', () {
+      expect(camelCase('Caps-first')).toEqual('capsFirst');
+    });
+  });
 }