Revert "clang: Makes builds with clang less dependent on absolute file path"

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index dde34c1eac64bd041b2d48ea0097d50efbde2b5e..60954b3dcc064e606e2db5f8ed1ac909c60b413f 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -307,15 +307,6 @@ config("compiler") {
     cflags += [ "-fcolor-diagnostics" ]
   }
 
-  # Makes builds independent of absolute file path.
-  # clang-cl (used if is_win) doesn't expose this flag.
-  # Currently disabled for nacl since its toolchain lacks this flag (too old).
-  # TODO(zforman): Once nacl's toolchain is updated, remove check.
-  if (is_clang && !is_win && !is_nacl) {
-    absolute_path = rebase_path("//.")
-    cflags += [ "-fdebug-prefix-map=$absolute_path=." ]
-  }
-
   # C++11 compiler flags setup.
   # ---------------------------
   if (is_linux || is_android || (is_nacl && is_clang)) {