Make guice build with javac 8.

javac 8 is more restrictive about generic type inference in situations
involving raw types, which prevents guice from compiling. This change
allows guice to be compiled with javac 8.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=55855098

core/src/com/google/inject/internal/ProvidedByInternalFactory.java

@@ -58,16 +58,15 @@ public void initialize(InjectorImpl injector, Errors errors) throws ErrorsExcept
     providerBinding =
         injector.getBindingOrThrow(providerKey, errors, JitLimitation.NEW_OR_EXISTING_JIT);
   }
-
-  @SuppressWarnings("unchecked")// 
+
   public T get(Errors errors, InternalContext context, Dependency dependency, boolean linked)
       throws ErrorsException {
     checkState(providerBinding != null, "not initialized");
 
     context.pushState(providerKey, providerBinding.getSource());
     try {
       errors = errors.withSource(providerKey);
-      Provider provider = providerBinding.getInternalFactory().get(
+      Provider<? extends T> provider = providerBinding.getInternalFactory().get(
           errors, context, dependency, true);
       return circularGet(provider, errors, context, dependency, linked, provisionCallback);
     } finally {

core/src/com/google/inject/spi/DefaultBindingTargetVisitor.java

@@ -69,9 +69,9 @@ public V visit(ConvertedConstantBinding<? extends T> convertedConstantBinding) {
     return visitOther(convertedConstantBinding);
   }
 
-   // javac says it's an error to cast ProviderBinding<? extends T> to Binding<? extends T>
   @SuppressWarnings("unchecked")
   public V visit(ProviderBinding<? extends T> providerBinding) {
-    return visitOther((Binding) providerBinding);
+    // TODO(cushon): remove raw (Binding) cast when we don't care about javac 6 anymore
+    return visitOther((Binding<? extends T>) (Binding) providerBinding);
   }
 }