resourceloader: Make JSMinPlus allow reserved words as property name (ES5)

This makes parse of "var a = { true: 12 };" and "var a = { true: 12 };"
possible thus making JSMinPlus ES5 compatible.

Bug: T215280
Change-Id: I84bcacf26ab8900d09958b5d961cc40e1a046698

2 files changed, 51 insertions, 3 deletions

diff --git a/includes/libs/jsminplus.php b/includes/libs/jsminplus.php
index 08e9d690db26..3134e50cfafb 100644
--- a/includes/libs/jsminplus.php
+++ b/includes/libs/jsminplus.php
@@ -1292,7 +1292,10 @@ class JSParser
 
 					if ($tt == OP_DOT)
 					{
-						$this->t->mustMatch(TOKEN_IDENTIFIER);
+						$tt = $this->t->get();
+						if (!$this->isKeyword($tt) && $tt !== TOKEN_IDENTIFIER)
+							throw $this->t->newSyntaxError("Unexpected token; token identifier or keyword expected.");
+
 						array_push($operands, new JSNode($this->t, OP_DOT, array_pop($operands), new JSNode($this->t)));
 					}
 					else
@@ -1427,6 +1430,11 @@ class JSParser
 							}
 							else
 							{
+								// Accept keywords as property names by treating
+								// them similarly with identifiers
+								if ($this->isKeyword($tt))
+									$tt = TOKEN_IDENTIFIER;
+
 								switch ($tt)
 								{
 									case TOKEN_IDENTIFIER:
@@ -1618,6 +1626,46 @@ class JSParser
 
 		return $n;
 	}
+
+	private function isKeyword($tt)
+	{
+		switch ($tt) {
+			case KEYWORD_BREAK:
+			case KEYWORD_CASE:
+			case KEYWORD_CATCH:
+			case KEYWORD_CONST:
+			case KEYWORD_CONTINUE:
+			case KEYWORD_DEBUGGER:
+			case KEYWORD_DEFAULT:
+			case KEYWORD_DELETE:
+			case KEYWORD_DO:
+			case KEYWORD_ELSE:
+			case KEYWORD_ENUM:
+			case KEYWORD_FALSE:
+			case KEYWORD_FINALLY:
+			case KEYWORD_FOR:
+			case KEYWORD_FUNCTION:
+			case KEYWORD_IF:
+			case KEYWORD_IN:
+			case KEYWORD_INSTANCEOF:
+			case KEYWORD_NEW:
+			case KEYWORD_NULL:
+			case KEYWORD_RETURN:
+			case KEYWORD_SWITCH:
+			case KEYWORD_THIS:
+			case KEYWORD_THROW:
+			case KEYWORD_TRUE:
+			case KEYWORD_TRY:
+			case KEYWORD_TYPEOF:
+			case KEYWORD_VAR:
+			case KEYWORD_VOID:
+			case KEYWORD_WHILE:
+			case KEYWORD_WITH:
+				return true;
+			default:
+				return false;
+		}
+	}
 }
 
 class JSCompilerContext
diff --git a/tests/phpunit/includes/libs/JavaScriptMinifierTest.php b/tests/phpunit/includes/libs/JavaScriptMinifierTest.php
index 54dc583b10e9..d57d0dd553cc 100644
--- a/tests/phpunit/includes/libs/JavaScriptMinifierTest.php
+++ b/tests/phpunit/includes/libs/JavaScriptMinifierTest.php
@@ -182,8 +182,8 @@ class JavaScriptMinifierTest extends PHPUnit\Framework\TestCase {
 
 			// Boolean minification (!0 / !1)
 			[ "var a = { b: true };", "var a={b:!0};" ],
-			[ "var a = { true: 12 };", "var a={true:12};", false ],
-			[ "a.true = 12;", "a.true=12;", false ],
+			[ "var a = { true: 12 };", "var a={true:12};" ],
+			[ "a.true = 12;", "a.true=12;" ],
 			[ "a.foo = true;", "a.foo=!0;" ],
 			[ "a.foo = false;", "a.foo=!1;" ],
 		];