Don't unify breaks in for loops with no update expression

before:

for (int x; //
    x < 42;
    ) {}

after:

for (int x; //
    x < 42; ) {}

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=154193916
diff --git a/core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java b/core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java
index d381455..1ed7194 100644
--- a/core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java
+++ b/core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java
@@ -984,8 +984,8 @@
       scan(node.getCondition(), null);
     }
     token(";");
-    builder.breakOp(" ");
     if (!node.getUpdate().isEmpty()) {
+      builder.breakOp(" ");
       builder.open(node.getUpdate().size() <= 1 ? ZERO : plusFour);
       boolean firstUpdater = true;
       for (ExpressionStatementTree updater : node.getUpdate()) {
@@ -998,6 +998,8 @@
       }
       builder.guessToken(";");
       builder.close();
+    } else {
+      builder.space();
     }
     builder.close();
     token(")");
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/B37629610.output b/core/src/test/resources/com/google/googlejavaformat/java/testdata/B37629610.output
index c3ea0da..9942776 100644
--- a/core/src/test/resources/com/google/googlejavaformat/java/testdata/B37629610.output
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/B37629610.output
@@ -2,8 +2,7 @@
   private static ImmutableList<InputOutputPair> toInputOutputPairs(Options options) {
     for (Iterator<Path> inputIt = options.inputJars.iterator(),
             outputIt = options.outputJars.iterator();
-        inputIt.hasNext();
-        ) {}
+        inputIt.hasNext(); ) {}
     for (Iterator<Path> inputIt = options.inputJars.iterator(),
             outputIt = options.outputJars.iterator();
         ;