Handle malformed annotations more gracefully

javac's parser doesn't weed annotations with illegal combinations
of assignment and non-assignment expressions, so don't crash when
formatting them.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=157855678

core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java

@@ -1232,7 +1232,11 @@ public Void visitAnnotation(AnnotationTree node, Void unused) {
             builder.breakOp(" ");
           }
         }
-        visitAnnotationArgument((AssignmentTree) argument);
+        if (argument instanceof AssignmentTree) {
+          visitAnnotationArgument((AssignmentTree) argument);
+        } else {
+          scan(argument, null);
+        }
         first = false;
       }
       builder.breakOp(UNIFIED, "", minusTwo, Optional.<BreakTag>absent());
@@ -1253,6 +1257,9 @@ public Void visitAnnotation(AnnotationTree node, Void unused) {
       new Predicate<ExpressionTree>() {
         @Override
         public boolean apply(ExpressionTree argument) {
+          if (!(argument instanceof AssignmentTree)) {
+            return false;
+          }
           ExpressionTree expression = ((AssignmentTree) argument).getExpression();
           return expression instanceof NewArrayTree
               && ((NewArrayTree) expression).getType() == null;

core/src/test/resources/com/google/googlejavaformat/java/testdata/B38352414.input

@@ -0,0 +1,2 @@
+@Redacted(Redacted.REDACTED + "/redacted", redacted = Redacted.class)
+class B38352414 {}

core/src/test/resources/com/google/googlejavaformat/java/testdata/B38352414.output

@@ -0,0 +1,2 @@
+@Redacted(Redacted.REDACTED + "/redacted", redacted = Redacted.class)
+class B38352414 {}