Revert "Define BASE_NUMERICS_DISABLE_OSTREAM_OPERATORS."

This reverts commit 9d8262e666811602d590888b282327086c194cdf.

Reason for revert: Does not integrate into Chromium.
Several Chromium //base headers are missing #include <ostream>.

Original change's description:
> Define BASE_NUMERICS_DISABLE_OSTREAM_OPERATORS.
>
> No existing code use the extra logging from third_party/base/numerics.
> Add missing includes to fix the build.
>
> Change-Id: I92462357d4bc54f20f12d647db9d19736c5babed
> Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/83955
> Commit-Queue: Lei Zhang <thestig@chromium.org>
> Reviewed-by: Tom Sepez <tsepez@chromium.org>

TBR=thestig@chromium.org,tsepez@chromium.org,pdfium-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: Iecbd68a10bf0b6f5eed8f7d7b3fded5c8d18379f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/83970
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcrt/widestring.cpp b/core/fxcrt/widestring.cpp
index 8d037b0..b38503f 100644
--- a/core/fxcrt/widestring.cpp
+++ b/core/fxcrt/widestring.cpp
@@ -10,7 +10,6 @@
 #include <string.h>
 
 #include <algorithm>
-#include <ostream>
 
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/fx_extension.h"
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index 5128631..5e8a2c1 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -560,19 +560,12 @@
   }
 }
 
-config("pdfium_base_config") {
-  defines = [ "BASE_NUMERICS_DISABLE_OSTREAM_OPERATORS" ]
-}
-
 source_set("pdfium_base") {
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
     "//build/config/compiler:no_chromium_code",
     ":pdfium_third_party_config",
   ]
-
-  public_configs = [ ":pdfium_base_config" ]
-
   sources = [
     "base/allocator/partition_allocator/address_space_randomization.cc",
     "base/allocator/partition_allocator/address_space_randomization.h",