Reapply "Enable full type-checks in checked mode."

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

Index: sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart b/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
index 89be18055f4cd9ae13848700598f4035227cb020..2eb8faa652971dd10d0ce8635695b03d76c3482f 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
@@ -1090,6 +1090,8 @@ abstract class HInstruction implements Spannable {
     } else if (kind == HTypeConversion.BOOLEAN_CONVERSION_CHECK) {
       // Boolean conversion checks work on non-nullable booleans.
       return new HTypeConversion(type, kind, HType.BOOLEAN, this);
+    } else if (kind == HTypeConversion.CHECKED_MODE_CHECK && !type.isRaw) {
+        throw 'creating compound check to $type (this = ${this})';
     } else {
       HType subtype = new HType.subtype(type, compiler);
       return new HTypeConversion(type, kind, subtype, this);
@@ -2155,7 +2157,6 @@ class HIndexAssign extends HInstruction {
   HInstruction get value => inputs[2];
 }
 
-// TODO(karlklose): use this class to represent type conversions as well.
 class HIs extends HInstruction {
   /// A check against a raw type: 'o is int', 'o is A'.
   static const int RAW_CHECK = 0;
@@ -2222,6 +2223,23 @@ class HTypeConversion extends HCheck {
     instructionType = type;
   }
 
+  HTypeConversion.withTypeRepresentation(this.typeExpression, this.kind,
+                                         HType type, HInstruction input,
+                                         HInstruction typeRepresentation)
+      : super(<HInstruction>[input, typeRepresentation]),
+        receiverTypeCheckSelector = null {
+    sourceElement = input.sourceElement;
+    instructionType = type;
+  }
+
+  bool get hasTypeRepresentation => inputs.length > 1;
+  HInstruction get typeRepresentation => inputs[1];
+
+  HInstruction convertType(Compiler compiler, DartType type, int kind) {
+    if (typeExpression == type) return this;
+    return super.convertType(compiler, type, kind);
+  }
+
   bool get isChecked => kind != NO_CHECK;
   bool get isCheckedModeCheck {
     return kind == CHECKED_MODE_CHECK