Make ruleById lookup table in rule set public

Saves about 500k function calls on a packagist update

src/Composer/DependencyResolver/RuleSet.php

@@ -22,6 +22,13 @@ class RuleSet implements \IteratorAggregate, \Countable
     const TYPE_JOB = 1;
     const TYPE_LEARNED = 4;
 
+    /**
+     * Lookup table for rule id to rule object
+     *
+     * @var array
+     */
+    public $ruleById;
+
     protected static $types = array(
         -1 => 'UNKNOWN',
         self::TYPE_PACKAGE => 'PACKAGE',
@@ -30,7 +37,6 @@ class RuleSet implements \IteratorAggregate, \Countable
     );
 
     protected $rules;
-    protected $ruleById;
     protected $nextRuleId;
 
     protected $rulesByHash;
@@ -76,11 +82,6 @@ class RuleSet implements \IteratorAggregate, \Countable
         return $this->nextRuleId;
     }
 
-    public function ruleById($id)
-    {
-        return $this->ruleById[$id];
-    }
-
     public function getRules()
     {
         return $this->rules;

src/Composer/DependencyResolver/Solver.php

@@ -56,7 +56,7 @@ class Solver
 
         $rulesCount = count($this->rules);
         for ($ruleIndex = 0; $ruleIndex < $rulesCount; $ruleIndex++) {
-            $rule = $this->rules->ruleById($ruleIndex);
+            $rule = $this->rules->ruleById[$ruleIndex];
 
             if (!$rule->isAssertion() || $rule->isDisabled()) {
                 continue;
@@ -687,7 +687,7 @@ class Solver
                     $i = 0;
                 }
 
-                $rule = $this->rules->ruleById($i);
+                $rule = $this->rules->ruleById[$i];
                 $literals = $rule->literals;
 
                 if ($rule->isDisabled()) {

tests/Composer/Test/DependencyResolver/RuleSetTest.php

@@ -76,7 +76,7 @@ class RuleSetTest extends TestCase
         $rule = new Rule($this->pool, array(), 'job1', null);
         $ruleSet->add($rule, RuleSet::TYPE_JOB);
 
-        $this->assertSame($rule, $ruleSet->ruleById(0));
+        $this->assertSame($rule, $ruleSet->ruleById[0]);
     }
 
     public function testGetIterator()