Optimize ParameterName

Don't re-tokenize the arguments unless their source text contains
something that looks like a parameter comment.

RELNOTES: N/A

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=170149858

core/src/main/java/com/google/errorprone/bugpatterns/ParameterName.java

@@ -85,10 +85,13 @@ private void checkArguments(
     }
     int start = ((JCTree) tree).getStartPosition();
     int end = state.getEndPosition(getLast(arguments));
+    String source = state.getSourceCode().subSequence(start, end).toString();
+    if (!NamedParameterComment.PARAMETER_COMMENT_PATTERN.matcher(source).find()) {
+      // fast path if the arguments don't contain anything that looks like a parameter comment
+      return;
+    }
     Deque<ErrorProneToken> tokens =
-        new ArrayDeque<>(
-            ErrorProneTokens.getTokens(
-                state.getSourceCode().subSequence(start, end).toString(), state.context));
+        new ArrayDeque<>(ErrorProneTokens.getTokens(source, state.context));
     forEachPair(
         sym.getParameters().stream(),
         arguments.stream(),