FULL PRODUCT VERSION :
javac 1.8.0-b128
java 1.8.0-b128

ADDITIONAL OS VERSION INFORMATION :
Linux x86/64

A DESCRIPTION OF THE PROBLEM :
javac crashes with a NullPointerException during generic bounds checking.

REGRESSION. Last worked in version 7u51

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b128)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b69, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run javac on the provided program.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Javac does not crash.
ACTUAL -
Javac crashes.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
An exception has occurred in the compiler (1.8.0-internal_bootstrap). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.NullPointerException
at com.sun.tools.javac.code.Types.closure(Types.java:3314)
at com.sun.tools.javac.code.Types.glb(Types.java:3637)
at com.sun.tools.javac.code.Types.capture(Types.java:3914)
at com.sun.tools.javac.code.Types.isSubtype(Types.java:836)
at com.sun.tools.javac.code.Types.isSubtype(Types.java:806)
at com.sun.tools.javac.code.Types$4.visitClassType(Types.java:258)
at com.sun.tools.javac.code.Types$4.visitClassType(Types.java:1)
at com.sun.tools.javac.code.Type$ClassType.accept(Type.java:763)
at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:4400)
at com.sun.tools.javac.code.Types.asSub(Types.java:234)
at com.sun.tools.javac.code.Types$10.visitClassType(Types.java:1570)
at com.sun.tools.javac.code.Types$10.visitClassType(Types.java:1)
at com.sun.tools.javac.code.Type$ClassType.accept(Type.java:763)
at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:4400)
at com.sun.tools.javac.code.Types.isCastable(Types.java:1490)
at com.sun.tools.javac.code.Types.notSoftSubtype(Types.java:1805)
at com.sun.tools.javac.comp.Check.checkExtends(Check.java:619)
at com.sun.tools.javac.comp.Check.firstIncompatibleTypeArg(Check.java:972)
at com.sun.tools.javac.comp.Check.access$4(Check.java:935)
at com.sun.tools.javac.comp.Check$Validator.visitTypeApply(Check.java:1254)
at com.sun.tools.javac.tree.JCTree$JCTypeApply.accept(JCTree.java:2129)
at com.sun.tools.javac.comp.Check$Validator.validateTree(Check.java:1350)
at com.sun.tools.javac.comp.Check$Validator.validateTrees(Check.java:1363)
at com.sun.tools.javac.comp.Check$Validator.visitTypeParameter(Check.java:1289)
at com.sun.tools.javac.tree.JCTree$JCTypeParameter.accept(JCTree.java:2218)
at com.sun.tools.javac.comp.Check$Validator.validateTree(Check.java:1350)
at com.sun.tools.javac.comp.Check.validate(Check.java:1221)
at com.sun.tools.javac.comp.Check.validate(Check.java:1218)
at com.sun.tools.javac.comp.Check.validate(Check.java:1228)
at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:4242)
at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4215)
at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4149)
at com.sun.tools.javac.comp.Attr.attrib(Attr.java:4124)
at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1251)
at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:904)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:863)
at com.sun.tools.javac.main.Main.compile(Main.java:523)
at com.sun.tools.javac.main.Main.compile(Main.java:381)
at com.sun.tools.javac.main.Main.compile(Main.java:370)
at com.sun.tools.javac.main.Main.compile(Main.java:361)
at com.sun.tools.javac.Main.compile(Main.java:56)
at com.sun.tools.javac.Main.main(Main.java:42)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
class One<X extends Two<? super X>> {}
class Two<Y extends Three<? extends Y>> implements Three<Y> {}
interface Three<Z> {}
---------- END SOURCE ----------