Fix a bunch of HTML compliance problems with LanguageExtensions.html
Fix a bunch of HTML compliance problems with LanguageExtensions.html

One weird thing is the addition of several <a name=""> tags where
previously there were id attributes on the <h3> tags. This is because
the id attribute must begin with a letter, not an underscore. The name
attribute is not so constrained, so links will continue to work.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@133677 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang