Fixed check style errors below:

/home/travis/build/square/wire/wire-compiler/src/main/java/com/squareup/wire/MessageWriter.java:134:45: '?' should be on a new line.
/home/travis/build/square/wire/wire-compiler/src/main/java/com/squareup/wire/MessageWriter.java:444:46: '?' should be on a new line.