Update tests to JavaSE-1.8

tests/org.eclipse.wtp.releng.tests/.classpath

 <?xml version="1.0" encoding="UTF-8"?>
 <classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
 	<classpathentry kind="con" path="org.eclipse.pde.core.requiredPlugins"/>
 	<classpathentry kind="src" path="src">
 		<attributes>

tests/org.eclipse.wtp.releng.tests/.settings/org.eclipse.jdt.core.prefs

 eclipse.preferences.version=1
 org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6
-org.eclipse.jdt.core.compiler.compliance=1.6
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
+org.eclipse.jdt.core.compiler.compliance=1.8
 org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
 org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
 org.eclipse.jdt.core.compiler.release=disabled
-org.eclipse.jdt.core.compiler.source=1.6
+org.eclipse.jdt.core.compiler.source=1.8

tests/org.eclipse.wtp.releng.tests/META-INF/MANIFEST.MF

@@ -14,5 +14,5 @@ Require-Bundle: org.eclipse.core.runtime,
  org.eclipse.equinox.p2.metadata;bundle-version="2.0.0",
  org.eclipse.equinox.p2.repository;bundle-version="2.0.0"
 Eclipse-LazyStart: true
-Bundle-RequiredExecutionEnvironment: JavaSE-1.6
+Bundle-RequiredExecutionEnvironment: JavaSE-1.8
 Bundle-ActivationPolicy: lazy