Note that we don't have any bots building official + GN + Xcode 5:
https://bugs.chromium.org/p/chromium/issues/detail?id=623685#c14

"""
ninja: Entering directory `out/gn'
[550/27006] LINK ./dump_syms
FAILED: dump_syms dump_syms.dSYM dump_syms.dSYM/Contents/Info.plist dump_syms.dSYM/Contents/Resources/DWARF/dump_syms 
TOOL_VERSION=1475877031 ../../build/toolchain/mac/linker_driver.py /Users/erikchen/goma/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang++  -Wcrl,dsym,.  -stdlib=libc++ -arch x86_64 -isysroot /Users/erikchen/projects/osx_sdks/MacOSX10.10.sdk -mmacosx-version-min=10.7 -Wl,-ObjC -Wl,-pie -Wcrl,strip,-x,-S -o "./dump_syms" -Wl,-filelist,"./dump_syms.rsp"  -framework Foundation
Assertion failed: (linked_addr_pos != line_table_map.end()), function FixReferences, file /SourceCache/dwarf_utilities/dwarf_utilities-114/source/DWARFdSYM.cpp, line 3710.
Traceback (most recent call last):
  File "../../build/toolchain/mac/linker_driver.py", line 222, in <module>
    Main(sys.argv)
  File "../../build/toolchain/mac/linker_driver.py", line 78, in Main
    linker_driver_outputs += linker_driver_actions[name](args)
  File "../../build/toolchain/mac/linker_driver.py", line 112, in <lambda>
    lambda full_args: action(sub_arg[len(name):], full_args))
  File "../../build/toolchain/mac/linker_driver.py", line 138, in RunDsymUtil
    subprocess.check_call(['xcrun', 'dsymutil', '-o', dsym_out, linker_out])
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 540, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['xcrun', 'dsymutil', '-o', './dump_syms.dSYM', './dump_syms']' returned non-zero exit status -6
"""