Fix integer issues leading to out of bounds access in fx_ge_text.cpp.

BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_config") {
   cflags = []
@@ skipping 1669 matching lines @@
   configs += [ ":pdfium_config" ]
 }
 
 test("pdfium_embeddertests") {
   sources = [
     "core/fpdfapi/fpdf_page/fpdf_page_func_embeddertest.cpp",
     "core/fpdfapi/fpdf_parser/cpdf_parser_embeddertest.cpp",
     "core/fpdfapi/fpdf_parser/fpdf_parser_decode_embeddertest.cpp",
     "core/fpdfapi/fpdf_render/fpdf_render_loadimage_embeddertest.cpp",
     "core/fpdfapi/fpdf_render/fpdf_render_pattern_embeddertest.cpp",
+    "core/fxge/ge/fx_ge_text_embeddertest.cpp",
     "fpdfsdk/fpdf_dataavail_embeddertest.cpp",
     "fpdfsdk/fpdfdoc_embeddertest.cpp",
     "fpdfsdk/fpdfedit_embeddertest.cpp",
     "fpdfsdk/fpdfext_embeddertest.cpp",
     "fpdfsdk/fpdfformfill_embeddertest.cpp",
     "fpdfsdk/fpdfsave_embeddertest.cpp",
     "fpdfsdk/fpdftext_embeddertest.cpp",
     "fpdfsdk/fpdfview_c_api_test.c",
     "fpdfsdk/fpdfview_c_api_test.h",
     "fpdfsdk/fpdfview_embeddertest.cpp",
@@ skipping 23 matching lines @@
       "//v8:v8_libplatform",
     ]
     include_dirs += [
       "//v8",
       "//v8/include",
     ]
     configs += [ "//v8:external_startup_data" ]
   }
   configs += [ ":pdfium_config" ]
 }