fix($parse): set null reference properties to undefined

When there is an expression of the form `true && a.b` and where `a == null`, then set
the value of `true || a()` to `undefined`.

Closes angular#12099

Author: lgalfaso

src/ng/parse.js

@@ -1024,6 +1024,8 @@ ASTCompiler.prototype = {
             expression = self.ensureSafeObject(expression);
             self.assign(intoId, expression);
             recursionFn(intoId);
+          }, function() {
+            self.assign(intoId, 'undefined');
           });
         });
       }

test/ng/parseSpec.js

@@ -1746,8 +1746,10 @@ describe('parser', function() {
         expect(scope.$eval("0||2")).toEqual(0 || 2);
         expect(scope.$eval("0||1&&2")).toEqual(0 || 1 && 2);
         expect(scope.$eval("true&&a")).toEqual(true && undefined);
+        expect(scope.$eval("true&&a()")).toEqual(true && undefined);
         expect(scope.$eval("true&&a.b")).toEqual(true && undefined);
         expect(scope.$eval("false||a")).toEqual(false || undefined);
+        expect(scope.$eval("false||a()")).toEqual(false || undefined);
         expect(scope.$eval("false||a.b")).toEqual(false || undefined);
       });