Bug 946083 - Part 1: Delete .class files when (re-)building a Java JAR. r=glandium

This cleans up stale .class files, so they don't get packaged into the
.jar files that Proguard consumes.

--HG--
extra : rebase_source : a090d707579711f85b8f9f174b88bf9302be0b24

config/makefiles/java-build.mk

@@ -83,9 +83,17 @@ ifdef JAVA_JAR_TARGETS #{
 # Arg 3: List of extra jars to link against.  We do not use VPATH so
 #        jars must be relative to $(CURDIR).
 # Arg 4: Additional JAVAC_FLAGS.
+
+# Note: Proguard fails when stale .class files corresponding to
+# removed inner classes are present in the object directory.  These
+# stale class files get packaged into the .jar file, which then gets
+# processed by Proguard.  To work around this, we always delete any
+# existing jarfile-classes directory and start fresh.
+
 define java_jar_template
 $(1): $(2) $(3)
 	$$(REPORT_BUILD)
+	@$$(RM) -rf $(1:.jar=)-classes
 	@$$(NSINSTALL) -D $(1:.jar=)-classes
 	@$$(if $$(filter-out .,$$(@D)),$$(NSINSTALL) -D $$(@D))
 	$$(JAVAC) $$(JAVAC_FLAGS)\