Fixes a few incorrect/unnecessary JsInterop checks

Change-Id: I518d53a737ec15be498978cd43b09e0030e11cc4
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JTypeOracle.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JTypeOracle.java
index a521e5b..9672583 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JTypeOracle.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JTypeOracle.java
@@ -571,7 +571,7 @@
    * True if the type is a JSO or interface implemented by a JSO, or a JsType, or a JsFunction.
    */
   public boolean canBeInstantiatedInJavascript(JType type) {
-    return canBeJavaScriptObject(type) || isOrExtendsJsType(type, false) || isJsFunction(type);
+    return canBeJavaScriptObject(type) || isJsType(type) || isJsFunction(type);
   }
 
   public boolean castFailsTrivially(JReferenceType fromType, JReferenceType toType) {
diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/ControlFlowAnalyzer.java b/dev/core/src/com/google/gwt/dev/jjs/impl/ControlFlowAnalyzer.java
index a6fb062..e18da72 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/ControlFlowAnalyzer.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/ControlFlowAnalyzer.java
@@ -29,7 +29,6 @@
 import com.google.gwt.dev.jjs.ast.JExpression;
 import com.google.gwt.dev.jjs.ast.JField;
 import com.google.gwt.dev.jjs.ast.JFieldRef;
-import com.google.gwt.dev.jjs.ast.JInstanceOf;
 import com.google.gwt.dev.jjs.ast.JInterfaceType;
 import com.google.gwt.dev.jjs.ast.JLocal;
 import com.google.gwt.dev.jjs.ast.JLocalRef;
@@ -304,17 +303,6 @@
     }
 
     @Override
-    public boolean visit(JInstanceOf x, Context ctx) {
-      JReferenceType targetType = x.getTestType();
-      if (program.typeOracle.isJsType(targetType)
-          && ((JDeclaredType) targetType).getJsPrototype() != null) {
-        // keep alive JsType with prototype used in cast so it can used in cast checks against JS objects later
-        rescue(targetType, true, true);
-      }
-      return true;
-    }
-
-    @Override
     public boolean visit(JInterfaceType type, Context ctx) {
       boolean isReferenced = referencedTypes.contains(type);
       boolean isInstantiated = instantiatedTypes.contains(type);