Add include guards to some generated files in core/css.

A couple of files in core/css were missing include guards which broke
jumbo builds.

R=fs@opera.com

Change-Id: I1d50e8b62f4926c054d51b48ab4f4edf5df5b76d
Reviewed-on: https://chromium-review.googlesource.com/565291Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: bratell at Opera <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#485272}

third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.h.tmpl

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#ifndef CSSPropertyDescriptor_h
+#define CSSPropertyDescriptor_h
+
 #include "core/CSSPropertyNames.h"
 #include "platform/heap/HeapAllocator.h"
 
@@ -26,3 +29,5 @@ struct CSSPropertyDescriptor {
 };
 
 }  // namespace blink
+
+#endif  // CSSPropertyDescriptor_h

third_party/WebKit/Source/build/scripts/templates/CSSValueIDMappingsGenerated.h.tmpl

 {% from 'macros.tmpl' import license %}
 {{license()}}
 
+#ifndef CSSValueIDMappingsGenerated_h
+#define CSSValueIDMappingsGenerated_h
+
 #include "base/logging.h"
 #include "core/CSSValueKeywords.h"
 #include "core/ComputedStyleBaseConstants.h"
@@ -51,3 +54,5 @@ inline CSSValueID platformEnumToCSSValueIDGenerated({{enum_name}} v) {
 } // namespace detail
 
 } // namespace blink
+
+#endif  // CSSValueIDMappingsGenerated_h