Exclude reusable blocks from the global block count

Modifies getGlobalBlockCount() to exclude reusable blocks from its
count. This fixes the block count including reusable blocks that have
been fetched and parsed but not inserted into the post or page.

packages/editor/src/store/selectors.js

@@ -729,7 +729,7 @@ export const getClientIdsWithDescendants = createSelector(
 export const getGlobalBlockCount = createSelector(
 	( state, blockName ) => {
 		if ( ! blockName ) {
-			return size( state.editor.present.blocks.byClientId );
+			return size( state.editor.present.blocks.byClientId ) - size( state.reusableBlocks.data );
 		}
 		return reduce(
 			state.editor.present.blocks.byClientId,

packages/editor/src/store/test/selectors.js

@@ -2523,12 +2523,37 @@ describe( 'selectors', () => {
 						},
 					},
 				},
+				reusableBlocks: {
+					data: {},
+				},
 			};
 
 			expect( getGlobalBlockCount( state ) ).toBe( 2 );
 		} );
 
-		it( 'should return the global umber of blocks of a given type', () => {
+		it( 'should exclude blocks referenced by reusable blocks from the count', () => {
+			const state = {
+				editor: {
+					present: {
+						blocks: {
+							byClientId: {
+								123: { clientId: 123, name: 'core/paragraph', attributes: {} },
+								456: { clientId: 456, name: 'core/paragraph', attributes: {} },
+							},
+						},
+					},
+				},
+				reusableBlocks: {
+					data: {
+						1: { clientId: 456 },
+					},
+				},
+			};
+
+			expect( getGlobalBlockCount( state ) ).toBe( 1 );
+		} );
+
+		it( 'should return the global number of blocks of a given type', () => {
 			const state = {
 				editor: {
 					present: {
@@ -2542,6 +2567,9 @@ describe( 'selectors', () => {
 						},
 					},
 				},
+				reusableBlocks: {
+					data: {},
+				},
 			};
 
 			expect( getGlobalBlockCount( state, 'core/heading' ) ).toBe( 1 );
@@ -2556,6 +2584,9 @@ describe( 'selectors', () => {
 						},
 					},
 				},
+				reusableBlocks: {
+					data: {},
+				},
 			};
 			expect( getGlobalBlockCount( state ) ).toBe( 0 );
 			expect( getGlobalBlockCount( state, 'core/heading' ) ).toBe( 0 );