CSL-M: Title case conversion bug with cs:layout extension

[zepinglee]

The variable is not correctly converted to title case if it's rendered in the layout with locale attribute (CSL-M extension). In the following test case, the cite item has "language": "en-US" and it is rendered with <layout locale="en">. Then the text-case="title" should be applied to the title "Review of book by A.N. author". In the output, the last word "author" is capitalized as expected but the word "book" remains lowercase.

      + expected - actual

      -Review of book by A.N. Author
      +Review of Book by A.N. Author

>>===== MODE =====>>
citation
<<===== MODE =====<<



>>===== RESULT =====>>
Review of Book by A.N. Author
<<===== RESULT =====<<


>>===== CSL =====>>
<style
      xmlns="http://purl.org/net/xbiblio/csl"
      class="note"
      default-locale="zh-CN"
      version="1.0">
  <info>
    <id />
    <title />
    <updated>2009-08-10T04:49:00+09:00</updated>
  </info>
  <citation>
    <layout locale="en">
      <text variable="title" text-case="title"/>
    </layout>
    <layout>
      <text variable="title" text-case="title"/>
    </layout>
  </citation>
</style>
<<===== CSL =====<<


>>===== INPUT =====>>
[
    {
        "id": "ITEM-1",
        "language": "en-US",
        "title": "Review of book by A.N. author",
        "type": "book"
    }
]
<<===== INPUT =====<<


>>===== VERSION =====>>
1.0
<<===== VERSION =====<<