Change List constructors.

sdk/lib/_internal/compiler/implementation/ssa/optimize.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart b/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
index 032ba03d6105aadfb44337c0e3e4aaca9576f95d..84e490805f069f4b5bcf8ac2230d83b400c493ff 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
@@ -219,11 +219,17 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
     DartType defaultClass = compiler.listClass.defaultClass;
     // TODO(ngeoffray): make sure that the only reason the List class is
     // not resolved is because it's not being used.
-    return element.isConstructor()
-        && defaultClass != null
-        && element.enclosingElement.declaration == defaultClass.element
-        && node.inputs.length == 2
-        && node.inputs[1].isInteger(types);
+    if (defaultClass == null) return false;
+    if (!element.isConstructor()) return false;
+    // TODO(ngeoffray): cache constructor.
+    if (element.enclosingElement.declaration != defaultClass.element) {
+      return false;
+    }
+    FunctionElement fixedLengthListConstructor =
+        compiler.listClass.lookupConstructor(
+            new Selector.callConstructor(const SourceString("fixedLength"),
+                                         compiler.listClass.getLibrary()));
+    return element == fixedLengthListConstructor.defaultImplementation;
   }
 
   HInstruction visitInvokeStatic(HInvokeStatic node) {
@@ -559,7 +565,7 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
   HInstruction visitFieldGet(HFieldGet node) {
     if (node.element == backend.jsArrayLength) {
       if (node.receiver is HInvokeStatic) {
-        // Try to recognize the length getter with input [:new List(int):].
+        // Try to recognize the length getter with input [:new List.fixedLength(int):].
         HInvokeStatic call = node.receiver;
         if (isFixedSizeListConstructor(call)) {
           return call.inputs[1];