Make Unreachable a regular RuntimeException to prepare migration to :utils.

Change-Id: If2ccbb58220d3b36abf33a467170c23903cb8258

src/main/java/com/android/tools/r8/errors/Unreachable.java

diff --git a/src/main/java/com/android/tools/r8/errors/Unreachable.java b/src/main/java/com/android/tools/r8/errors/Unreachable.java
index 0232c99..3b0b89a 100644
--- a/src/main/java/com/android/tools/r8/errors/Unreachable.java
+++ b/src/main/java/com/android/tools/r8/errors/Unreachable.java
@@ -3,10 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 package com.android.tools.r8.errors;
 
-/**
- * Exception to signal an expected unreachable code path.
- */
-public class Unreachable extends InternalCompilerError {
+/** Exception to signal an expected unreachable code path. */
+public class Unreachable extends RuntimeException {
 
   public static Unreachable raise() {
     throw new Unreachable();

src/test/java/com/android/tools/r8/D8IncrementalRunExamplesJava9Test.java

diff --git a/src/test/java/com/android/tools/r8/D8IncrementalRunExamplesJava9Test.java b/src/test/java/com/android/tools/r8/D8IncrementalRunExamplesJava9Test.java
index c126083..01224fd 100644
--- a/src/test/java/com/android/tools/r8/D8IncrementalRunExamplesJava9Test.java
+++ b/src/test/java/com/android/tools/r8/D8IncrementalRunExamplesJava9Test.java
@@ -8,6 +8,7 @@
 import com.android.tools.r8.errors.CompilationError;
 import com.android.tools.r8.errors.InternalCompilerError;
 import com.android.tools.r8.errors.Unimplemented;
+import com.android.tools.r8.errors.Unreachable;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.AndroidApp;
 import java.io.IOException;
@@ -67,7 +68,7 @@
       try {
         AndroidApp app = ToolHelper.runD8(builder, this::combinedOptionConsumer);
         assert app.getDexProgramResourcesForTesting().size() == 1;
-      } catch (Unimplemented | CompilationError | InternalCompilerError re) {
+      } catch (Unimplemented | CompilationError | Unreachable | InternalCompilerError re) {
         throw re;
       } catch (RuntimeException re) {
         throw re.getCause() == null ? re : re.getCause();

src/test/java/com/android/tools/r8/D8RunExamplesAndroidPTest.java

diff --git a/src/test/java/com/android/tools/r8/D8RunExamplesAndroidPTest.java b/src/test/java/com/android/tools/r8/D8RunExamplesAndroidPTest.java
index 0ae485a..80ede40 100644
--- a/src/test/java/com/android/tools/r8/D8RunExamplesAndroidPTest.java
+++ b/src/test/java/com/android/tools/r8/D8RunExamplesAndroidPTest.java
@@ -7,6 +7,7 @@
 import com.android.tools.r8.errors.CompilationError;
 import com.android.tools.r8.errors.InternalCompilerError;
 import com.android.tools.r8.errors.Unimplemented;
+import com.android.tools.r8.errors.Unreachable;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import java.nio.file.Path;
 import java.util.function.UnaryOperator;
@@ -42,7 +43,7 @@
           .setOutput(out, OutputMode.DexIndexed);
       try {
         ToolHelper.runD8(builder, this::combinedOptionConsumer);
-      } catch (Unimplemented | CompilationError | InternalCompilerError re) {
+      } catch (Unimplemented | CompilationError | Unreachable | InternalCompilerError re) {
         throw re;
       } catch (RuntimeException re) {
         throw re.getCause() == null ? re : re.getCause();