Extract DiagnosticReporter implementation from Compiler.

pkg/compiler/lib/src/js_backend/patch_resolver.dart

Index: pkg/compiler/lib/src/js_backend/patch_resolver.dart
diff --git a/pkg/compiler/lib/src/js_backend/patch_resolver.dart b/pkg/compiler/lib/src/js_backend/patch_resolver.dart
index 0949c8fbace9cdd0e692259e0b5741dc004eeccc..d827a3e97224bdaa3abc3ea253f1cf6e04247364 100644
--- a/pkg/compiler/lib/src/js_backend/patch_resolver.dart
+++ b/pkg/compiler/lib/src/js_backend/patch_resolver.dart
@@ -31,13 +31,13 @@ class PatchResolverTask extends CompilerTask {
   FunctionElement resolveExternalFunction(FunctionElementX element) {
     if (element.isPatched) {
       FunctionElementX patch = element.patch;
-      compiler.withCurrentElement(patch, () {
+      reporter.withCurrentElement(patch, () {
         patch.computeType(resolution);
       });
       checkMatchingPatchSignatures(element, patch);
       element = patch;
     } else {
-      compiler.reportErrorMessage(
+      reporter.reportErrorMessage(
          element, MessageKind.PATCH_EXTERNAL_WITHOUT_IMPLEMENTATION);
     }
     return element;
@@ -62,8 +62,8 @@ class PatchResolverTask extends CompilerTask {
       DartType originParameterType = originParameter.computeType(resolution);
       DartType patchParameterType = patchParameter.computeType(resolution);
       if (originParameterType != patchParameterType) {
-        compiler.reportError(
-            compiler.createMessage(
+        reporter.reportError(
+            reporter.createMessage(
                 originParameter,
                 MessageKind.PATCH_PARAMETER_TYPE_MISMATCH,
                 {'methodName': origin.name,
@@ -71,7 +71,7 @@ class PatchResolverTask extends CompilerTask {
                  'originParameterType': originParameterType,
                  'patchParameterType': patchParameterType}),
             <DiagnosticMessage>[
-              compiler.createMessage(
+              reporter.createMessage(
                   patchParameter,
                   MessageKind.PATCH_POINT_TO_PARAMETER,
                   {'parameterName': patchParameter.name}),
@@ -89,15 +89,15 @@ class PatchResolverTask extends CompilerTask {
             // We special case the list constructor because of the
             // optional parameter.
             && origin != compiler.unnamedListConstructor) {
-          compiler.reportError(
-              compiler.createMessage(
+          reporter.reportError(
+              reporter.createMessage(
                   originParameter,
                   MessageKind.PATCH_PARAMETER_MISMATCH,
                   {'methodName': origin.name,
                    'originParameter': originParameterText,
                    'patchParameter': patchParameterText}),
               <DiagnosticMessage>[
-                  compiler.createMessage(
+                  reporter.createMessage(
                       patchParameter,
                       MessageKind.PATCH_POINT_TO_PARAMETER,
                       {'parameterName': patchParameter.name}),
@@ -116,10 +116,10 @@ class PatchResolverTask extends CompilerTask {
     FunctionSignature patchSignature = patch.functionSignature;
 
     if (originSignature.type.returnType != patchSignature.type.returnType) {
-      compiler.withCurrentElement(patch, () {
+      reporter.withCurrentElement(patch, () {
         Node errorNode =
             patchTree.returnType != null ? patchTree.returnType : patchTree;
-        compiler.reportErrorMessage(
+        reporter.reportErrorMessage(
             errorNode, MessageKind.PATCH_RETURN_TYPE_MISMATCH,
             {'methodName': origin.name,
              'originReturnType': originSignature.type.returnType,
@@ -128,8 +128,8 @@ class PatchResolverTask extends CompilerTask {
     }
     if (originSignature.requiredParameterCount !=
         patchSignature.requiredParameterCount) {
-      compiler.withCurrentElement(patch, () {
-        compiler.reportErrorMessage(
+      reporter.withCurrentElement(patch, () {
+        reporter.reportErrorMessage(
             patchTree,
             MessageKind.PATCH_REQUIRED_PARAMETER_COUNT_MISMATCH,
             {'methodName': origin.name,
@@ -145,8 +145,8 @@ class PatchResolverTask extends CompilerTask {
         patchSignature.optionalParameterCount != 0) {
       if (originSignature.optionalParametersAreNamed !=
           patchSignature.optionalParametersAreNamed) {
-        compiler.withCurrentElement(patch, () {
-          compiler.reportErrorMessage(
+        reporter.withCurrentElement(patch, () {
+          reporter.reportErrorMessage(
               patchTree,
               MessageKind.PATCH_OPTIONAL_PARAMETER_NAMED_MISMATCH,
               {'methodName': origin.name});
@@ -155,8 +155,8 @@ class PatchResolverTask extends CompilerTask {
     }
     if (originSignature.optionalParameterCount !=
         patchSignature.optionalParameterCount) {
-      compiler.withCurrentElement(patch, () {
-        compiler.reportErrorMessage(
+      reporter.withCurrentElement(patch, () {
+        reporter.reportErrorMessage(
             patchTree,
             MessageKind.PATCH_OPTIONAL_PARAMETER_COUNT_MISMATCH,
             {'methodName': origin.name,