Remove warning for running the compiler under Java 6/7

Now the compiler won't even start, so no need to check this manually.

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.java

@@ -79,9 +79,6 @@ public abstract class CommonCompilerArguments implements Serializable {
     @Argument(value = "Xno-check-impl", description = "Do not check presence of 'impl' modifier in multi-platform projects")
     public boolean noCheckImpl;
 
-    @Argument(value = "Xskip-java-check", description = "Do not warn when running the compiler under Java 6 or 7")
-    public boolean noJavaVersionWarning;
-
     @Argument(value = "Xcoroutines=warn")
     public boolean coroutinesWarn;
 

compiler/cli/src/org/jetbrains/kotlin/cli/common/CLICompiler.java

@@ -18,7 +18,6 @@ package org.jetbrains.kotlin.cli.common;
 
 import com.intellij.openapi.Disposable;
 import com.intellij.openapi.util.Disposer;
-import com.intellij.openapi.util.SystemInfo;
 import kotlin.collections.ArraysKt;
 import org.fusesource.jansi.AnsiConsole;
 import org.jetbrains.annotations.NotNull;
@@ -142,7 +141,6 @@ public abstract class CLICompiler<A extends CommonCompilerArguments> {
         }
 
         reportUnknownExtraFlags(messageCollector, arguments);
-        reportUnsupportedJavaVersion(messageCollector, arguments);
 
         GroupingMessageCollector groupingCollector = new GroupingMessageCollector(messageCollector);
 
@@ -337,16 +335,6 @@ public abstract class CLICompiler<A extends CommonCompilerArguments> {
         }
     }
 
-    private void reportUnsupportedJavaVersion(MessageCollector collector, A arguments) {
-        if (!SystemInfo.isJavaVersionAtLeast("1.8") && !arguments.noJavaVersionWarning) {
-            collector.report(
-                    CompilerMessageSeverity.STRONG_WARNING,
-                    "Running the Kotlin compiler under Java 6 or 7 is unsupported and will no longer be possible in a future update.",
-                    CompilerMessageLocation.NO_LOCATION
-            );
-        }
-    }
-
     @NotNull
     protected abstract ExitCode doExecute(
             @NotNull A arguments,