Test for bug 15380: XPath: id('foo') doesn't resolve correctly.

  
id('nested1') PASSED: [object HTMLDivElement]
id('nested1')/div[1] PASSED: [object HTMLDivElement]
id('nested1')//div[1] PASSED: [object HTMLDivElement]
id('nested1')/div[1]/input[2] PASSED: [object HTMLInputElement]
id('nested1')/div[1]//input[2] PASSED: [object HTMLInputElement]
id('nested1')//div[1]/input[2] PASSED: [object HTMLInputElement]
id('nested1')//div[1]//input[2] PASSED: [object HTMLInputElement]