Avoid |call| when calling actions with one parameter.

This speeds up the benchmark suite execution by 0.18%, which may just be a
measurement error. (Standrad statistic tests would tell more, but I don't want
to mess with them now.) The code is little bit nicer this way though.

Going further and avoiding |apply| seems to slow thigs down a bit, possibly
because multiple array accesses. I may try improved version without array
accesses (where Action passes the Sequence variable names to save the results
into) sometime later.

Detailed results (benchmark suite totals):

---------------------------------
 Test #     Before       After
---------------------------------
      1   29.08 kB/s   28.91 kB/s
      2   28.72 kB/s   28.75 kB/s
      3   28.78 kB/s   28.88 kB/s
      4   28.57 kB/s   28.90 kB/s
      5   28.84 kB/s   28.81 kB/s
---------------------------------
Average   28.80 kB/s   28.85 kB/s
---------------------------------

Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/533.2 (KHTML, like Gecko) Chrome/5.0.342.9 Safari/533.2

lib/compiler.js

@@ -1020,37 +1020,39 @@ PEG.Grammar.Action.prototype.compile = function(resultVar) {
 
   var expressionResultVar = PEG.Compiler.generateUniqueIdentifier("result");
 
-  var paramCount =  this._expression instanceof PEG.Grammar.Sequence
-    ? this._expression.getElements().length
-    : 1;
-
-  var params = PEG.ArrayUtils.map(
-    PEG.ArrayUtils.range(1, paramCount + 1),
-    function(n) { return "$" + n; }
-  ).join(", ");
-
-  var actionFunction = PEG.Compiler.formatCode(
-    "function(${params}) { ${action} }",
-    {
-      params: params,
-      action: this._action
-    }
-  );
-
-  var invokeFunctionName = this._expression instanceof PEG.Grammar.Sequence
-    ? "apply"
-    : "call";
+  if (this._expression instanceof PEG.Grammar.Sequence) {
+    var params = PEG.ArrayUtils.map(
+      PEG.ArrayUtils.range(1, this._expression.getElements().length + 1),
+      function(n) { return "$" + n; }
+    ).join(", ");
+
+    var invocationCode = PEG.Compiler.formatCode(
+      "(function(${params}) { ${action} }).apply(null, ${expressionResultVar})",
+      {
+        params:              params,
+        action:              this._action,
+        expressionResultVar: expressionResultVar
+      }
+    );
+  } else {
+    var invocationCode = PEG.Compiler.formatCode(
+      "(function($1) { ${action} })(${expressionResultVar})",
+      {
+        action:              this._action,
+        expressionResultVar: expressionResultVar
+      }
+    );
+  }
 
   return PEG.Compiler.formatCode(
     "${expressionCode}",
     "var ${resultVar} = ${expressionResultVar} !== null",
-    "  ? (${actionFunction}).${invokeFunctionName}(this, ${expressionResultVar})",
+    "  ? ${invocationCode}",
     "  : null;",
     {
       expressionCode:      this._expression.compile(expressionResultVar),
       expressionResultVar: expressionResultVar,
-      actionFunction:      actionFunction,
-      invokeFunctionName:  invokeFunctionName,
+      invocationCode:      invocationCode,
       resultVar:           resultVar
     }
   );