Fix sky include guards to match Chromium style

sky/engine/wtf/dtoa/double-conversion.h

Index: sky/engine/wtf/dtoa/double-conversion.h
diff --git a/sky/engine/wtf/dtoa/double-conversion.h b/sky/engine/wtf/dtoa/double-conversion.h
index a357c75909070d6fafebe655fd0e346e29bcb181..497e644b1d311a474bb7f3e86e6224849642969e 100644
--- a/sky/engine/wtf/dtoa/double-conversion.h
+++ b/sky/engine/wtf/dtoa/double-conversion.h
@@ -25,8 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
-#define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
+#ifndef SKY_ENGINE_WTF_DTOA_DOUBLE-CONVERSION_H_
+#define SKY_ENGINE_WTF_DTOA_DOUBLE-CONVERSION_H_
 
 #include "sky/engine/wtf/dtoa/utils.h"
 
@@ -374,4 +374,4 @@ namespace double_conversion {
 
 } // namespace WTF
 
-#endif  // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
+#endif  // SKY_ENGINE_WTF_DTOA_DOUBLE-CONVERSION_H_