Author: Olivier Tilloy <olivier.tilloy@canonical.com>
Description: revert of 074fa51f85b15ad2e2d6c804a03825d48dbeb063, which requires Clang r313108 (unreleased yet)

--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -501,18 +501,6 @@ config("compiler") {
     }
   }
 
-  if (is_clang && !is_nacl && current_toolchain == host_toolchain &&
-      target_os != "chromeos") {
-    cflags += [
-      # TODO(hans): Remove this once Clang generates better optimized debug info
-      # by default. https://crbug.com/765793
-      "-Xclang",
-      "-mllvm",
-      "-Xclang",
-      "-instcombine-lower-dbg-declare=0",
-    ]
-  }
-
   # Print absolute paths in diagnostics. There is no precedent for doing this
   # on Linux/Mac (GCC doesn't support it), but MSVC does this with /FC and
   # Windows developers rely on it (crbug.com/636109) so only do this on Windows.