address review comments (instanceof usage on StatementCoverage)

Move declaration of TestCoverageCount before its usage

packages/plugin-ext/src/plugin/types-impl.ts

@@ -3330,6 +3330,11 @@ export class TestMessage implements theia.TestMessage {
     constructor(public message: string | theia.MarkdownString) { }
 }
 
+@es5ClassCompat
+export class TestCoverageCount {
+    constructor( public covered: number,  public total: number) { }
+}
+
 @es5ClassCompat
 export class FileCoverage {
 
@@ -3341,7 +3346,7 @@ export class FileCoverage {
         const decl = new TestCoverageCount(0, 0);
 
         for (const detail of details) {
-            if (StatementCoverage.is(detail)) {
+            if (detail instanceof StatementCoverage) {
                 statements.total += 1;
                 statements.covered += detail.executed ? 1 : 0;
 
@@ -3380,12 +3385,6 @@ export class StatementCoverage implements theia.StatementCoverage {
     constructor(public executed: number | boolean, public location: Position | Range, public branches: BranchCoverage[] = []) { }
 }
 
-export namespace StatementCoverage {
-    export function is(coverage: unknown): coverage is StatementCoverage {
-        return isObject(coverage) && 'branches' in coverage;
-    }
-}
-
 export class BranchCoverage implements theia.BranchCoverage {
     constructor(public executed: number | boolean, public location?: Position | Range, public label?: string) { }
 }
@@ -3394,10 +3393,6 @@ export class BranchCoverage implements theia.BranchCoverage {
 export class DeclarationCoverage implements theia.DeclarationCoverage {
     constructor(public name: string, public executed: number | boolean, public location: Position | Range) { }
 }
-@es5ClassCompat
-export class TestCoverageCount implements theia.TestCoverageCount {
-    constructor( public covered: number,  public total: number) { }
-}
 
 export type FileCoverageDetail = StatementCoverage | DeclarationCoverage;