Enforce correct number comparisons when inlining Array.indexOf.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index c923d2c2f787b16f3e0ec5674f5763731b7cede5..20f86bf5207341ffb1e03f52ff162e053dc16547 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -8808,6 +8808,12 @@ HValue* HOptimizedGraphBuilder::BuildArrayIndexOf(HValue* receiver,
 
   Push(graph()->GetConstantMinus1());
   if (IsFastDoubleElementsKind(kind) || IsFastSmiElementsKind(kind)) {
+    // Make sure that we can actually compare numbers correctly below, see
+    // https://code.google.com/p/chromium/issues/detail?id=407946 for details.
+    search_element = AddUncasted<HForceRepresentation>(
+        search_element, IsFastSmiElementsKind(kind) ? Representation::Smi()
+                                                    : Representation::Double());
+
     LoopBuilder loop(this, context(), direction);
     {
       HValue* index = loop.BeginBody(initial, terminating, token);
@@ -8815,12 +8821,8 @@ HValue* HOptimizedGraphBuilder::BuildArrayIndexOf(HValue* receiver,
           elements, index, static_cast<HValue*>(NULL),
           kind, ALLOW_RETURN_HOLE);
       IfBuilder if_issame(this);
-      if (IsFastDoubleElementsKind(kind)) {
-        if_issame.If<HCompareNumericAndBranch>(
-            element, search_element, Token::EQ_STRICT);
-      } else {
-        if_issame.If<HCompareObjectEqAndBranch>(element, search_element);
-      }
+      if_issame.If<HCompareNumericAndBranch>(element, search_element,
+                                             Token::EQ_STRICT);
       if_issame.Then();
       {
         Drop(1);