Makes descriptors hold nullptr for properties not implemented in API.

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

Index: third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
diff --git a/third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl b/third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
index 457060f0e4c2e1601451339999db441ff99cb75c..ee077dc7822fe383a5c3f46ae095ec2aa389ebdd 100644
--- a/third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
+++ b/third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
@@ -14,14 +14,23 @@ static_assert(
     "CSSPropertyDescriptor must be a POD to support using initializer lists.");
 
 static CSSPropertyDescriptor cssPropertyDescriptors[] = {
-    // An invalid CSSPropertyDescriptor. When functions are added to
-    // CSSPropertyAPI, add a nullptr to represent their function pointers in the
-    // struct initaliser.
-    { nullptr, false },
-    // When functions are added to CSSPropertyAPI, also add them to the struct
-    // initaliser below.
+    // An invalid CSSPropertyDescriptor.
+    {

[sashab, 2017/02/01 17:50:20]

YAY getting rid of code dependencies!! \o/

+      {% for valid_api_method in valid_api_methods %}
+        nullptr,
+      {% endfor %}
+    },
+    // CSSPropertyDescriptors for all valid properties.
     {% for api_class in api_classes %}
-    { {{api_class.classname}}::parseSingleValue, true },
+    {
+      {% for api_method in api_methods %}
+        {% if api_method in api_class.api_methods %}

[sashab, 2017/02/01 17:50:20]

You can merge these:

{% for foo in bar if baz %}

Also be careful with your indenting -- see other tmpl files -- the indenting
needs to match C++, not Jinja2, so don't indent {%'s unless the C++ should be
indented :)

[aazzam, 2017/02/01 22:33:16]

done :) that makes things look a bit nicer!

+          {{api_class.classname}}::{{api_method}},
+        {% else %}
+           nullptr,

[sashab, 2017/02/01 17:50:20]

One thing I'm worried about here is ordering. Since the descriptor is not
generated, we don't know the order these APIs will appear in, e.g if valid
values is [parseShorthand, parseSingleValue] all this code will fail.

This is OK for now because we can just add a comment to CSSProperties.json5, but
yet another reason to move to IDL. :)

[aazzam, 2017/02/01 22:33:15]

ahhh I didn't even notice the ordering issue! that is a bit annoying

+        {% endif %}
+      {% endfor %}
+    },
     {% endfor %}
 };