Add support for generating external types in ComputedStyleBase.

third_party/WebKit/Source/build/scripts/templates/ComputedStyleBase.cpp.tmpl

 {% from 'macros.tmpl' import license %}
 {{license()}}
 
 #include "core/ComputedStyleBase.h"
 #include "wtf/SizeAssertions.h"
 
 namespace blink {
 
 struct SameSizeAsComputedStyleBase {
-  unsigned m_bitfields[{{expected_total_field_bytes}}];
+  {% for field in fields|rejectattr("is_bit_field") %}
+  {{field.type_name}} {{field.name}}};
+  {% endfor %}
+  unsigned m_bit_fields[{{expected_bit_field_bytes}}];
 };
 // If this fails, the packing algorithm in make_computed_style_base.py has
 // failed to produce the optimal packed size. To fix, update the algorithm to
 // ensure that the buckets are placed so that each takes up at most 1 word.
 ASSERT_SIZE(ComputedStyleBase, SameSizeAsComputedStyleBase);
 
 void ComputedStyleBase::inheritFrom(const ComputedStyleBase& inheritParent,
                                     IsAtShadowBoundary isAtShadowBoundary) {
   {% for field in fields if field.is_inherited %}
   {{field.name}} = inheritParent.{{field.name}};
   {% endfor %}
 }
 
 void ComputedStyleBase::copyNonInheritedFromCached(
     const ComputedStyleBase& other) {
   {% for field in fields if (field.is_property and not field.is_inherited) or field.is_inherited_flag %}
   {{field.name}} = other.{{field.name}};
   {% endfor %}
 }
 
 void ComputedStyleBase::propagateIndependentInheritedProperties(
     const ComputedStyleBase& parentStyle) {
   {% for field in fields if field.is_property and field.is_independent %}
   if ({{field.is_inherited_method_name}}())
     {{field.setter_method_name}}(parentStyle.{{field.getter_method_name}}());
   {% endfor %}
 }
 
 } // namespace blink