Add range information to external array loads.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc	(revision 10454)
+++ src/hydrogen-instructions.cc	(working copy)
@@ -1339,7 +1339,24 @@
 }
 
 
+Range* HLoadKeyedSpecializedArrayElement::InferRange() {
+  switch (elements_kind()) {
+    case EXTERNAL_PIXEL_ELEMENTS:
+      return new Range(0, 255);
+    case EXTERNAL_BYTE_ELEMENTS:
+      return new Range(-128, 127);
+    case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
+      return new Range(0, 255);
+    case EXTERNAL_SHORT_ELEMENTS:
+      return new Range(-32768, 32767);
+    case EXTERNAL_UNSIGNED_SHORT_ELEMENTS:
+      return new Range(0, 65535);
+    default:
+      return HValue::InferRange();
+  }
+}
 
+
 void HCompareGeneric::PrintDataTo(StringStream* stream) {
   stream->Add(Token::Name(token()));
   stream->Add(" ");