Short-circuit Asset CDN in AMP responses

modules/photon-cdn.php

@@ -39,6 +39,17 @@ public static function go() {
 	public static function cdnize_assets() {
 		global $wp_scripts, $wp_styles, $wp_version;
 
+		/*
+		 * Short-circuit if AMP since not relevant as custom JS is not allowed and CSS is inlined.
+		 * Note that it is not suitable to use the jetpack_force_disable_site_accelerator filter for this
+		 * because it will be applied before the wp action, which is the point at which the queried object
+		 * is available and we know whether the response will be AMP or not. This is particularly important
+		 * for AMP-first (native AMP) pages where there are no AMP-specific URLs.
+		 */
+		if ( Jetpack_AMP_Support::is_amp_request() ) {
+			return;
+		}
+
 		/**
 		 * Filters Jetpack CDN's Core version number and locale. Can be used to override the values
 		 * that Jetpack uses to retrieve assets. Expects the values to be returned in an array.
@@ -92,6 +103,12 @@ public static function cdnize_assets() {
 	 * @return string The expected relative path for the CDN-ed URL.
 	 */
 	public static function fix_script_relative_path( $relative, $src ) {
+
+		// Note relevant in AMP responses. See note above.
+		if ( Jetpack_AMP_Support::is_amp_request() ) {
+			return $relative;
+		}
+
 		$strpos = strpos( $src, '/wp-includes/' );
 
 		// We only treat URLs that have wp-includes in them. Cases like language textdomains