move SkTextBox into utils

BUG=skia:
TBR=

Review URL: https://codereview.chromium.org/696293005
diff --git a/gyp/utils.gypi b/gyp/utils.gypi
index 7d40a8b..5148491 100644
--- a/gyp/utils.gypi
+++ b/gyp/utils.gypi
@@ -37,6 +37,7 @@
         '<(skia_include_path)/utils/SkRandom.h',
         '<(skia_include_path)/utils/SkRTConf.h',
         '<(skia_include_path)/utils/SkProxyCanvas.h',
+        '<(skia_include_path)/utils/SkTextBox.h',
         '<(skia_include_path)/utils/SkWGL.h',
 
         '<(skia_src_path)/utils/SkBase64.cpp',
@@ -86,6 +87,7 @@
         '<(skia_src_path)/utils/SkSHA1.cpp',
         '<(skia_src_path)/utils/SkSHA1.h',
         '<(skia_src_path)/utils/SkRTConf.cpp',
+        '<(skia_src_path)/utils/SkTextBox.cpp',
         '<(skia_src_path)/utils/SkTextureCompressor.cpp',
         '<(skia_src_path)/utils/SkTextureCompressor.h',
         '<(skia_src_path)/utils/SkTextureCompressor_Utils.h',