Added CSSPropertyAPIMethods.json5 which defines all API methods.

third_party/WebKit/Source/core/BUILD.gn

Index: third_party/WebKit/Source/core/BUILD.gn
diff --git a/third_party/WebKit/Source/core/BUILD.gn b/third_party/WebKit/Source/core/BUILD.gn
index 425812b5eda6fda202f62809b7ce8935f3fc36ec..247069f888d93d472fe33b66458c87efbd21280d 100644
--- a/third_party/WebKit/Source/core/BUILD.gn
+++ b/third_party/WebKit/Source/core/BUILD.gn
@@ -411,17 +411,6 @@ css_properties("make_core_generated_computed_style_base") {
   ]
 }
 
-css_properties("make_core_generated_css_property_apis") {
-  script = "../build/scripts/make_css_property_apis.py"
-  other_inputs = [
-    "../build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl",
-    "../build/scripts/templates/CSSPropertyAPIFiles.h.tmpl",
-  ]
-  outputs = [
-    "$blink_core_output_dir/css/properties/CSSPropertyDescriptor.cpp",
-  ]
-}
-
 css_properties("make_core_generated_css_property_names") {
   script = "../build/scripts/make_css_property_names.py"
   outputs = [
@@ -488,6 +477,16 @@ css_properties("make_core_generated_css_property_metadata") {
   ]
 }
 
+make_css_property_apis("make_core_generated_css_property_apis") {
+  in_files = [
+    "css/CSSProperties.json5",
+    "css/properties/CSSPropertyAPIMethods.json5",
+  ]
+  outputs = [
+    "$blink_core_output_dir/css/properties/CSSPropertyDescriptor.cpp",
+  ]
+}
+
 process_in_files("make_core_generated_css_value_keywords") {
   script = "../build/scripts/make_css_value_keywords.py"