Early returns from BalsaFrame::HasInvalidHeaderChars().

This makes the code easier to follow.

PiperOrigin-RevId: 761074394

quiche/balsa/balsa_frame.cc

diff --git a/quiche/balsa/balsa_frame.cc b/quiche/balsa/balsa_frame.cc
index 9a15420..c9cfae2 100644
--- a/quiche/balsa/balsa_frame.cc
+++ b/quiche/balsa/balsa_frame.cc
@@ -670,20 +670,19 @@
       headers->OriginalHeaderStreamBegin() + lines.front().first;
   const char* stream_end =
       headers->OriginalHeaderStreamBegin() + lines.back().second;
-  bool found_invalid = false;
 
   for (const char* c = stream_begin; c < stream_end; c++) {
     if (header_properties::IsInvalidHeaderChar(*c)) {
-      found_invalid = true;
+      return true;
     }
     if (*c == '\r' &&
         http_validation_policy().disallow_lone_cr_in_request_headers &&
         c + 1 < stream_end && *(c + 1) != '\n') {
-      found_invalid = true;
+      return true;
     }
   }
 
-  return found_invalid;
+  return false;
 }
 
 void BalsaFrame::ProcessHeaderLines(const Lines& lines, bool is_trailer,