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

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 abstract class OptimizationPhase {
   String get name;
   void visitGraph(HGraph graph);
 }
@@ skipping 588 matching lines @@
       } else if (expressionMask.intersection(typeMask, compiler).isEmpty) {
         return graph.addConstantBool(false, constantSystem);
       }
     }
     return node;
   }
 
   HInstruction visitTypeConversion(HTypeConversion node) {
     HInstruction value = node.inputs[0];
     DartType type = node.typeExpression;
-    if (type != null && (!type.isRaw || type.kind == TypeKind.TYPE_VARIABLE)) {
-      return node;
-    }
+    if (type != null && !type.isRaw) return node;
     HType convertedType = node.instructionType;
     if (convertedType.isUnknown()) return node;
     HType combinedType = value.instructionType.intersection(
         convertedType, compiler);
     return (combinedType == value.instructionType) ? value : node;
   }
 
   Element findConcreteFieldForDynamicAccess(HInstruction receiver,
                                             Selector selector) {
     HType receiverType = receiver.instructionType;
@@ skipping 96 matching lines @@
     }
 
     HInstruction receiver = node.getDartReceiver(compiler);
     Element field = findConcreteFieldForDynamicAccess(receiver, node.selector);
     if (field == null || !field.isAssignable()) return node;
     // Use [:node.inputs.last:] in case the call follows the
     // interceptor calling convention, but is not a call on an
     // interceptor.
     HInstruction value = node.inputs.last;
     if (compiler.enableTypeAssertions) {
-      DartType type = field.computeType(compiler);
-      if (!type.isRaw || type.kind == TypeKind.TYPE_VARIABLE) {
-        // We cannot generate the correct type representation here, so don't
-        // inline this access.
-        return node;
-      }
       HInstruction other = value.convertType(
           compiler,
-          type,
+          field.computeType(compiler),
           HTypeConversion.CHECKED_MODE_CHECK);
       if (other != value) {
         node.block.addBefore(node, other);
         value = other;
       }
     }
     return new HFieldSet(field, receiver, value);
   }
 
   HInstruction visitStringConcat(HStringConcat node) {
@@ skipping 967 matching lines @@
     HBasicBlock block = user.block;
     block.addAfter(user, interceptor);
     block.rewrite(user, interceptor);
     block.remove(user);
 
     // The interceptor will be removed in the dead code elimination
     // phase. Note that removing it here would not work because of how
     // the [visitBasicBlock] is implemented.
   }
 }