Remove unused enum TextRun::TextCodePath

New Clang versions warn that kAuto shadows LengthType::kAuto. It's easy to fix
because the enum isn't used at all.

Bug: 895475
Change-Id: I04c63a9ff87afdb08b060a987bc7a160fecc62e4
Reviewed-on: https://chromium-review.googlesource.com/c/1283691
Commit-Queue: Hans Wennborg <hans@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600065}

third_party/blink/renderer/platform/text/text_run.h

@@ -50,8 +50,6 @@ class PLATFORM_EXPORT TextRun final {
     kAllowLeadingExpansion = 1 << 1,
   };
 
-  enum TextCodePath { kAuto = 0, kForceSimple = 1, kForceComplex = 2 };
-
   typedef unsigned ExpansionBehavior;
 
   TextRun(const LChar* c,