Fix crash on CSS @import with variable name

Follows-up a1173e7 (I8220cd808f), which introduced this crash by
evaluating import nodes much earlier but lacking a try-catch for cases
that don't need to be compiled by LESS. We missed this in CI because
the upstream urls.less is disabled pending T353147.

Follows-up e7ed93f (Iddd8e41137), which regressed path compilation
such that it outputs filesystem paths where URLs are expected.

Bug: T361035
Change-Id: I302e7527c2b72eebbc26f85fa0ff2f54b5988abc

lib/Less/ImportVisitor.php

@@ -45,11 +45,13 @@ public function visitImport( $importNode, &$visitDeeper ) {
 	}
 
 	public function processImportNode( $importNode, $env, &$importParent ) {
-		$inlineCSS = $importNode->options['inline'];
+		$evaldImportNode = $inlineCSS = $importNode->options['inline'];
 
-		// TODO: We might need upstream's try-catch here
-		// try { … } catch ( e ) { importNode.css = true; importNode.error = e; }
-		$evaldImportNode = $importNode->compileForImport( $env );
+		try {
+			$evaldImportNode = $importNode->compileForImport( $env );
+		} catch ( Exception $e ) {
+			$importNode->css = true;
+		}
 
 		if ( $evaldImportNode && ( !$evaldImportNode->css || $inlineCSS ) ) {
 

lib/Less/Tree/Import.php

@@ -143,7 +143,7 @@ public function compilePath( $env ) {
 				$pathValue = $path->value;
 				// Add the base path if the import is relative
 				if ( $pathValue && Less_Environment::isPathRelative( $pathValue ) ) {
-					$path->value = $rootpath . $pathValue;
+					$path->value = $this->currentFileInfo['uri_root'] . $pathValue;
 				}
 			}
 			$path->value = Less_Environment::normalizePath( $path->value );

test/Fixtures/less.php/css/T361035-variable-name.css

@@ -0,0 +1 @@
+@import "test.css";

test/Fixtures/less.php/less/T361035-variable-name.less

@@ -0,0 +1,5 @@
+.add_an_import(@file_to_import) {
+	@import "@{file_to_import}";
+}
+
+.add_an_import("test.css");