mac: use -std=c++11 instead of -std=gnu++11.

Linux and Android need some more work before this can
happen there. No intended behavior change.

BUG=427584

Review URL: https://codereview.chromium.org/679143004

Cr-Commit-Position: refs/heads/master@{#302310}

build/common.gypi

@@ -4075,8 +4075,10 @@
               '-Wno-reserved-user-defined-literal',
             ],
             'cflags_cc': [
-              # See the comment in the Mac section for what it takes to move
-              # this to -std=c++11.
+              # gnu++11 instead of c++11 is needed because some code uses
+              # typeof() (a GNU extension).
+              # TODO(thakis): Eventually switch this to c++11 instead,
+              # http://crbug.com/427584
               '-std=gnu++11',
             ],
           }],
@@ -4831,12 +4833,7 @@
             # Note that the prebuilt Clang binaries should not be used for iOS
             # development except for ASan builds.
             ['clang==1', {
-              # gnu++11 instead of c++11 is needed because some code uses
-              # typeof() (a GNU extension).
-              # TODO(thakis): Eventually switch this to c++11 instead of
-              # gnu++11 (once typeof can be removed, which is blocked on c++11
-              # being available everywhere).
-              'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++11',  # -std=gnu++11
+              'CLANG_CXX_LANGUAGE_STANDARD': 'c++11',  # -std=c++11
               # Warn if automatic synthesis is triggered with
               # the -Wobjc-missing-property-synthesis flag.
               'CLANG_WARN_OBJC_MISSING_PROPERTY_SYNTHESIS': 'YES',